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[Illustration: Frontispiece.

"Come forth into the light of things,
Let Nature be your Teacher."

--WORDSWORTH.]




STUDIES OF TREES

BY
J.J. LEVISON, M.F.
Lecturer on Ornamental and Shade Trees, Yale University Forest School;
Forester to the Department of Parks, Brooklyn, N.Y.

FIRST EDITION
FIRST THOUSAND

1914




PREFACE


In presenting this volume, the author is aware that there are several
excellent books, dealing with one phase or another of tree life, already
before the public. It is believed, however, that there is still need for
an all-round book, adapted to the beginner, which gives in a brief and
not too technical way the most important facts concerning the
identification, structure and uses of our more common trees, and which
considers their habits, enemies and care both when growing alone and
when growing in groups or forests.

In the chapters on the identification of trees, the aim has been to
bring before the student only such characters and facts as shall help
him to distinguish the tree readily during all seasons of the year.
Special stress is laid in each case on the most striking peculiarities.
Possible confusion with other trees of similar appearance is prevented
as far as possible through comparisons with trees of like form or habit.

Only such information is given concerning the structure and requirements
of trees as will enable the reader better to understand the subsequent
chapters. In the second half of the book, practical application is made
of the student's general knowledge thus acquired, and he is acquainted
with the fundamental principles of planting, care, forestry, wood
identification and nature study.

The author recognizes the vastness of the field he is attempting to
cover and the impossibility of even touching, in a small hand-book of
this character, on every phase of tree study. He presumes no further;
yet he hopes that by adhering to what is salient and by eliminating the
less important, though possibly interesting, facts, he is able to offer
a general and elementary _résumé_ of the whole subject of value to
students, private owners, farmers and teachers.

In the preparation of Chapter VIII on "Our Common Woods: Their
Identification, Properties and Uses," considerable aid has been received
from Prof. Samuel J. Record, author of "Economic Woods of the United
States." Acknowledgment is also due to the U.S. Forest Service for the
photographs used in Figs. 18, 122 to 138 inclusive and 142; to Dr.
George B. Sudworth, Dendrologist of the U.S. Forest Service, for
checking up the nomenclature in the lists of trees under Chapter V; to
Dr. E.P. Felt, Entomologist of the State of New York, for suggestions in
the preparation of the section of the book relating to insects; to Dr.
W.A. Murrill, Assistant Director of the New York Botanical Gardens, for
Fig. 108; and to Mr. Hermann W. Merkel, Chief Forester of the New York
Zoological Park, for Figs. 26, 59 and 60.

J.J. LEVISON.

BROOKLYN, N.Y.
June, 1914.




CONTENTS


CHAPTER I

HOW TO IDENTIFY TREES
  The Pines
  The Spruce and Hemlock
  The Red Cedar and Arbor-vitae


CHAPTER II

HOW TO IDENTIFY TREES (Continued)
  The Larch and Cypress
  The Horsechestnut, Ash, and Maple
  Trees Told by their Form
  Trees Told by their Bark or Trunk
  The Oaks and Chestnut


CHAPTER III

HOW TO IDENTIFY TREES (Continued)
  The Hickories, Walnut, and Butternut
  Tulip Tree, Sweet Gum, Linden, Magnolia, Locust, Catalpa, Dogwood,
      Mulberry, and Osage Orange


CHAPTER IV

THE STRUCTURE AND REQUIREMENTS OF TREES


CHAPTER V

WHAT TREES TO PLANT AND HOW
  Trees for the Lawn
  Trees for the Street
  Trees for Woodland
  Trees for Screening


CHAPTER VI

THE CARE OF TREES
  Insects Injurious to Trees and How to Combat Them
  Important Insects
  Tree Diseases
  Pruning Trees
  Tree Repair


CHAPTER VII

FORESTRY
  What Forestry Is and What It Does
  Care of the Woodland


CHAPTER VIII

OUR COMMON WOODS: THEIR IDENTIFICATION, PROPERTIES AND USES
  Woods Without Pores (Soft woods)
  Woods with Pores (Hard woods)


CHAPTER IX

AN OUTDOOR LESSON ON TREES




INTRODUCTION


A good many popular books on trees have been published in the United
States in recent years. The continually increasing demand for books of
this character indicates the growing public interest not only in the
trees that we pass in our daily walks, but also in the forest considered
as a community of trees, because of its aesthetic and protective value
and its usefulness as a source of important economic products.

As a nation, we are thinking more about trees and woods than we were
wont to do in the years gone by. We are growing to love the trees and
forests as we turn more and more to outdoor life for recreation and
sport. In our ramblings along shady streets, through grassy parks, over
wooded valleys, and in mountain wildernesses we find that much more than
formerly we are asking ourselves what are these trees, what are the
leaf, flower, twig, wood and habit characteristics which distinguish
them from other trees; how large do they grow; under what conditions of
soil and climate do they thrive best; what are their enemies and how can
they be overcome; what is their value for wood and other useful
products; what is their protective value; are they useful for planting
along streets and in parks and in regenerating forests; how can the
trees of our streets and lawns be preserved and repaired as they begin
to fail from old age or other causes? All these questions and many more
relating to the important native and exotic trees commonly found in the
states east of the Great Lakes and north of Maryland Mr. Levison has
briefly answered in this book. The author's training as a forester and
his experience as a professional arboriculturist has peculiarly fitted
him to speak in an authoritative and interesting way about trees and
woods.

The value of this book is not in new knowledge, but in the simple
statement of the most important facts relating to some of our common
trees, individually and collectively considered. A knowledge of trees
and forests adds vastly to the pleasures of outdoor life. The more we
study trees and the more intimate our knowledge of the forest as a unit
of vegetation in which each tree, each flower, each animal and insect
has its part to play in the complete structure, the greater will be our
admiration of the wonderful beauty and variety exhibited in the trees
and woods about us.

J.W. TOUMEY,
Director, Yale University Forest School.

NEW HAVEN, CONN.,
June, 1914.




STUDIES OF TREES




CHAPTER I

HOW TO IDENTIFY TREES


There are many ways in which the problem of identifying trees may be
approached. The majority attempt to recognize trees by their leaf
characters. Leaf characters, however, do not differentiate the trees
during the other half of the year when they are bare. In this chapter
the characterizations are based, as far as possible, on peculiarities
that are evident all year round. In almost every tree there is some one
trait that marks its individuality and separates it, at a glance, from
all other trees. It may be the general form of the tree, its mode of
branching, bark, bud or fruit. It may be some variation in color, or, in
case of the evergreen trees, it may be the number and position of the
needles or leaves. The species included in the following pages have thus
been arranged in groups based on these permanent characters. The
individual species are further described by a distinguishing paragraph
in which the main character of the tree is emphasized in heavy type.

The last paragraph under each species is also important because it
classifies all related species and distinguishes those that are liable
to be confused with the particular tree under consideration.



GROUP I. THE PINES

[Illustration: FIG. 1.--Twig of the Austrian Pine.]

How to tell them from other trees: The pines belong to the _coniferous_
    class of trees; that is, trees which bear cones. The pines may be
    told from the other coniferous trees by their leaves, which are in
    the form of _needles_ two inches or more in length. These needles
    keep green throughout the entire year. This is characteristic of all
    coniferous trees, except the larch and cypress, which shed their
    leaves in winter.

[Illustration: FIG. 2.--Twig of the White Pine.]

    The pines are widely distributed throughout the Northern Hemisphere,
    and include about 80 distinct species with over 600 varieties. The
    species enumerated here are especially common in the eastern part of
    the United states, growing either native in the forest or under
    cultivation in the parks. The pines form a very important class of
    timber trees, and produce beautiful effects when planted in groups
    in the parks.

How to tell them from each other: The pine needles are arranged in
    _clusters_; see Fig. 1. Each species has a certain characteristic
    number of needles to the cluster and this fact generally provides
    the simplest and most direct way of distinguishing the different
    pines.

    In the white pine there are _five_ needles to each cluster, in the
    pitch pine _three_, and in the Scotch pine _two_. The Austrian pine
    also has two needles to the cluster, but the difference in size and
    character of the needles will distinguish this species from the
    Scotch pine.


THE WHITE PINE (_Pinus strobus_)

Distinguishing characters: The tree can be told at close range by the
    number of needles to each cluster, Fig. 2. There are *five* needles
    to each cluster of the white pine. They are bluish green, slender,
    and about four inches in length.

    At a distance the tree may be told by the *right angles* which the
    branches form with the main trunk, Fig. 3. No other pine shows this
    character.

Form and size: A tall tree, the stateliest of the evergreens.

Range: Eastern North America.

Soil and location: Prefers a deep, sandy soil, but will grow in almost
    any soil.

Enemies: Sucking insects forming white downy patches on the bark and
    twigs, the _white pine weevil_, a boring insect, and the _white pine
    blister rust_, a fungus, are among its principal enemies.

[Illustration: FIG. 3.--The White Pine.]

Value for planting: Aside from its value as an ornamental tree, the
    white pine is an excellent tree to plant on abandoned farms and for
    woodlands and windbreaks throughout the New England States, New
    York, Pennsylvania, and the Lake States.

Commercial value: The wood is easily worked, light, durable, and will
    not warp. It is used for naval construction, lumber, shingles,
    laths, interior finish, wooden ware, etc.

Other characters: The _fruit_ is a cone, four to six inches long.

Comparisons: The tree is apt to be confused with the _Bhotan pine_
    (_Pinus excelsa_), which is commonly grown as an ornamental tree.
    The Bhotan pine, however, has needles much longer and more drooping
    in appearance.


THE PITCH PINE (_Pinus rigida_)

Distinguishing characters: Here there are *three* needles to each
    cluster, Fig. 4. They are dark, yellowish-green needles about four
    inches long. The rough-looking _branches_ of the tree may be seen
    _studded with cones_ throughout the year, and _clusters of leaves_
    may be seen _sprouting directly from the trunk_ of the tree; see
    Fig. 5. The last two are very characteristic and will distinguish
    the tree at a glance.


Form and size: It is a low tree of uncertain habit and extremely rough
    looking at every stage of its life. It is constantly full of dead
    branches and old cones which persist on the tree throughout the
    year.

Range: Eastern United States.

Soil and location: Grows in the poorest and sandiest soils where few
    other trees will grow. In New Jersey and on Long Island where it is
    native, it proves so hardy and persistent that it often forms pure
    stands excluding other trees.

[Illustration: FIG. 4.--Twig of the Pitch Pine.]

Enemies: None of importance.

Value for planting: Well adapted for the sea coast and other exposed
    places. It is of extremely uncertain habit and is subject to the
    loss of the lower limbs. It frequently presents a certain
    picturesqueness of outline, but it could not be used as a specimen
    tree on the lawn.

[Illustration: FIG. 5.--The Pitch Pine.]

Commercial value: The wood is coarse grained and is used for rough
    lumber, fuel, and charcoal.

Other characters: The _fruit_ is a cone one to three
inches long, persistent on the tree for several years.


THE SCOTCH PINE (_Pinus sylvestris_)

Distinguishing characters: There are *two* needles to each cluster, and
    these are _short_ compared with those of the white pine, and
    _slightly twisted_; see Fig. 6. The _bark_, especially along the
    upper portion of the trunk, _is reddish_ in color.

Form and size: A medium-sized tree with a short crown.

Range: Europe, Asia, and eastern United States.

Soil and location: Will do best on a deep, rich, sandy soil, but will
    also grow on a dry, porous soil.

Enemies: In Europe the Scotch pine has several insect enemies, but in
    America it appears to be free from injury.

Value for planting: Suitable for windbreaks and woodland planting. Many
    excellent specimens may also be found in our parks.

Commercial value: In the United States, the wood is chiefly used for
    fuel, though slightly used for barrels, boxes, and carpentry. In
    Europe, the Scotch pine is an important timber tree.

Comparisons: The Scotch pine is apt to be confused with the _Austrian
    pine_ (_Pinus austriaca_), because they both have two needles to
    each cluster. The needles of the Austrian pine, however, are much
    longer, coarser, straighter, and darker than those of the Scotch
    pine; Fig. 1. The form of the Austrian pine, too, is more
    symmetrical and compact.

[Illustration: FIG. 6.--Twig of the Scotch Pine.]

    The _red pine_ (_Pinus resinosa_) is another tree that has two
    needles to each cluster, but these are much longer than those of the
    Scotch pine (five to six inches) and are straighter. The bark, which
    is reddish in color, also differentiates the red pine from the
    Austrian pine. The position of the cones on the red pine, which
    point outward and downward at maturity, will also help to
    distinguish this tree from the Scotch and the Austrian varieties.



GROUP II. THE SPRUCE AND HEMLOCK

How to tell them from other trees: The spruce and hemlock belong to the
    evergreen class and may be told from the other trees by their
    _leaves_. The characteristic leaves of the spruce are shown in Fig.
    9; those of the hemlock in Fig. 10. These are much shorter than the
    needles of the pines but are longer than the leaves of the red cedar
    or arbor vitae. They are neither arranged in clusters like those of
    the larch, nor in feathery layers like those of the cypress. They
    adhere to the tree throughout the year, while the leaves of the
    larch and cypress shed in the fall.

    The spruces are pyramidal-shaped trees, with tall and tapering
    trunks, thickly covered with branches, forming a compact crown. They
    are widely distributed throughout the cold and temperate regions of
    the northern hemisphere, where they often form thick forests over
    extended areas.

    There are eighteen recognized species of spruce. The Norway spruce
    has been chosen as a type for this group because it is so commonly
    planted in the northeastern part of the United States.

    The hemlock is represented by seven species, confined to temperate
    North America, Japan, and Central and Western China.

[Illustration: FIG. 7.--The Norway Spruce.]

How to tell them from each other: The needles and branches of the spruce
    are _coarse_; those of the hemlock are _flat and graceful_. The
    individual leaves of the spruce, Fig. 9, are four-sided and green or
    blue on the under side, while those of the hemlock, Fig. 10, are
    flat and are _marked by two white lines_ on the under side.


THE NORWAY SPRUCE (_Picea excelsa_)

Distinguishing characters: The characteristic appearance of the
    full-grown tree is due to the *drooping branchlets* carried on *main
    branches which bend upward* (Fig. 7).

Leaf: The leaves are dark green in color and are _arranged spirally_,
    thus making the twigs coarser to the touch than the twigs of the
    hemlock or fir. In cross-section, the individual leaflet is
    quadrilateral, while that of the pine is triangular.

Form and size: A large tree with a straight, undivided trunk and a
    well-shaped, conical crown (Fig. 7).

Range: Northern Europe, Asia, northern North America.

Soil and location: Grows in cool, moist situations.

Enemies: The foliage of the spruce is sometimes affected by _red
    spider_, but is apt to be more seriously injured by drought, wind,
    and late frosts.

Value for planting: Commonly planted as an ornamental tree and for
    hedges. It does well for this purpose in a cool northern climate,
    but in the vicinity of New York City and further south it does not
    do as well, losing its lower branches at an early age, and becoming
    generally scraggly in appearance.

[Illustration: FIG. 8.--A Group of Hemlock.]

Commercial value: The wood is light and soft and is used for
    construction timber, paper pulp, and fuel.

Other characters: The _fruit_ is a large slender cone, four to seven
    inches long.

Comparisons: The _white spruce_ (_Picea canadensis_) may be told from
    the Norway spruce by the whitish color on the under side of its
    leaves and the unpleasant, pungent odor emitted from the needles
    when bruised. The cones of the white spruce, about two inches long,
    are shorter than these of the Norway spruce, but are longer than
    those of the black spruce.

    It is essentially a northern tree growing in all sorts of locations
    along the streams and on rocky mountain slopes as far north as the
    Arctic Sea and Alaska. It often appears as an ornamental tree as far
    south as New York and Pennsylvania.

    The _black spruce_ (_Picea mariana_) may be told from the other
    spruces by its small cone, which is usually only about one inch in
    length. In New England it seldom grows to as large a size as the
    other spruce trees.

    It covers large areas in various parts of northern North America and
    grows to its largest size in Manitoba. The black spruce has little
    value as an ornamental tree.

    The _Colorado blue spruce_ (_Picea parryana_ or _Picea pungens_)
    which is commonly used as an ornamental tree on lawns and in parks,
    can be told from the other spruces by its pale-blue or sage-green
    color and its sharp-pointed, coarse-feeling twigs. Its small size
    and sharp-pointed conical form are also characteristic.

    It grows to a large size in Colorado and the Middle West. In the
    Eastern States and in northern Europe where it is planted as an
    ornamental tree, it is usually much smaller.

[Illustration: FIG. 9.--Twig of the Norway Spruce.]


HEMLOCK (_Tsuga canadensis_)

Distinguishing characters: Its leaves are arranged in *flat layers*,
    giving a flat, horizontal and graceful appearance to the whole
    branch (Fig. 8). The individual leaves are dark green above, lighter
    colored below, and are *marked by two white lines on the under side*
    (Fig. 10).

    The leaves are arranged on little stalks, a characteristic that does
    not appear in the other evergreen trees.

Form and size: A large tree with a broad-based pyramidal head, and a
    trunk conspicuously tapering toward the apex. The branches extend
    almost to the ground.

Range: The hemlock is a northern tree, growing in Canada and the United
    States.

Soil and location: Grows on all sorts of soils, in the deepest woods as
    well as on high mountain slopes.

Enemies: None of importance.

Value for planting: The hemlock makes an excellent hedge because it
    retains its lowest branches and will stand shearing. In this respect
    it is preferable to the spruce. It makes a fair tree for the lawn
    and is especially desirable for underplanting in woodlands, where
    the shade from the surrounding trees is heavy. In this respect it is
    like the beech.

Commercial value: The wood is soft, brittle, and coarse-grained, and is
    therefore used mainly for coarse lumber. Its bark is so rich in
    tannin that it forms one of the chief commercial products of the
    tree.

Other characters: The _fruit_ is a small cone about ¾ of an inch long,
    which generally hangs on the tree all winter.

[Illustration: FIG. 10.--Twig of the Hemlock.]



GROUP III. THE RED CEDAR AND ARBOR-VITAE

How to tell them from other trees: The red cedar (juniper) and
    arbor-vitae may be told from other trees by their _leaves_, which
    remain on the tree and keep green throughout the entire year. These
    leaves differ from those of the other evergreens in being much
    shorter and of a distinctive shape as shown in Figs. 12 and 13. The
    trees themselves are much smaller than the other evergreens
    enumerated in this book. Altogether, there are thirty-five species
    of juniper recognized and four of arbor-vitae. The junipers are
    widely distributed over the northern hemisphere, from the Arctic
    region down to Mexico in the New World, and in northern Africa,
    China, and Japan in the Old World. The arbor-vitae is found in
    northeastern and northwestern America, China, and Japan. The species
    mentioned here are those commonly found in America.

How to tell them from each other: The _twigs_ of the arbor-vitae are
    _flat and fan-like_ as in Fig. 13; the twigs of the red cedar are
    _needle-shaped or scale-like_ as in Fig. 12. The foliage of the
    arbor-vitae is of a lighter color than that of the red cedar, which
    is sombre green. The arbor-vitae will generally be found growing in
    moist locations, while the red cedar will grow in dry places as
    well. The arbor-vitae generally retains its lower branches in open
    places, while the branches of the red cedar start at some distance
    from the ground.


RED CEDAR (_Juniperus virginiana_)

[Illustration: FIG. 11.--The Red Cedar.]

Distinguishing characters: The tree can best be told at a glance by its
    general form, size and leaves. It is a medium-sized tree with a
    _symmetrical, cone-like form_, Fig. 11, which, however, broadens
    out somewhat when the tree grows old. Its color throughout the year
    is dull green with a tinge of brownish red, and its bark peels in
    thin strips.

[Illustration:
FIG. 12(a).--Twig of Young Cedar.
FIG. 12(b).--Twig of Cedar (Older Tree).]

Leaf: In young trees the leaf is needle-shaped, pointed, and marked by a
    white line on its under side, Fig. 12(a). In older trees it is
    scale-like, Fig. 12(b), and the white line on its under side is
    indistinct.

Range: Widely distributed over nearly all of eastern and central North
    America.

Soil and location: Grows on poor, gravelly soils as well as in rich
    bottom lands.

Enemies: The "_cedar apple_," commonly found on this tree, represents a
    stage of the apple rust, and for that reason it is not desirable to
    plant such trees near orchards. Its wood is also sometimes attacked
    by small _boring insects_.

Value for planting: Its characteristic slender form gives the red cedar
    an important place as an ornamental tree, but its chief value lies
    in its commercial use.

Commercial value: The wood is durable, light, smooth and fragrant, and
    is therefore used for making lead-pencils, cabinets, boxes,
    moth-proof chests, shingles, posts, and telegraph poles.

Other characters: The _fruit_ is small, round and berry-like, about the
    size of a pea, of dark blue color, and carries from one to four bony
    seeds.

Other common names: The red cedar is also often called _juniper_ and
    _red juniper_.

Comparisons: The red cedar is apt to be confused with the _low juniper_
    (_Juniperus communis_) which grows in open fields all over the
    world. The latter, however, is generally of a low form with a flat
    top. Its leaves are pointed and prickly, never scale-like, and they
    are whitish above and green below. Its bark shreds and its fruit is
    a small round berry of agreeable aromatic odor.


ARBOR-VITAE; NORTHERN WHITE CEDAR (_Thuja occidentalis_)

Distinguishing characters: The *branchlets* are extremely *flat and
    fan-like*, Fig. 13, and have an agreeable _aromatic odor_ when
    bruised. The tree is an evergreen with a _narrow conical form_.

[Illustration: FIG. 13.--Twig of the Arbor-vitae.]

Leaf: Leaves of two kinds, one scale-like and flat, the other keeled,
    all tightly pressed to the twig (see Fig. 13).

Form and size: A close, conical head with dense foliage near the base.
    Usually a small tree, but in some parts of the northeastern States
    it grows to medium size with a diameter of two feet.

Range: Northern part of North America.

Soil and location: Inhabits low, swampy lands; in the State of Maine
    often forming thick forests.

Enemies: Very seldom affected by insects.

Value for planting: Is hardy in New England, where it is especially used
    for hedges. It is also frequently used as a specimen tree on the
    lawn.

Commercial value: The wood is durable for posts, ties, and shingles. The
    bark contains considerable tannin and the juices from the tree have
    a medicinal value.

Other characters: The _fruit_ is a cone about ½ inch long.

Other common names: Arbor-vitae is sometimes called _white cedar_ and
    _cedar_.

Comparisons: The arbor-vitae is apt to be confused with the true _white
    cedar_ (_Chamaecyparis thyoides_) but the leaves of the latter are
    sharp-pointed and not flattened or fan-shaped.




CHAPTER II

HOW TO IDENTIFY TREES--(Continued)



GROUP IV. THE LARCH AND CYPRESS

How to tell them from other trees: In summer the larch and cypress may
    easily be told from other trees by their _leaves_. These are
    needle-shaped and arranged in clusters with numerous leaves to each
    cluster in the case of the larch, and feathery and flat in the case
    of the cypress. In winter, when their leaves have dropped off, the
    trees can be told by their cones, which adhere to the branches.

    There are nine recognized species of larch and two of bald cypress.
    The larch is characteristically a northern tree, growing in the
    northern and mountainous regions of the northern hemisphere from the
    Arctic circle to Pennsylvania in the New World, and in Central
    Europe, Asia, and Japan in the Old World. It forms large forests in
    the Alps of Switzerland and France.

    The European larch and not the American is the principal species
    considered here, because it is being planted extensively in this
    country and in most respects is preferable to the American species.

    The bald cypress is a southern tree of ancient origin, the
    well-known cypress of Montezuma in the gardens of Chepultepec having
    been a species of Taxodium. The tree is now confined to the swamps
    and river banks of the South Atlantic and Gulf States, where it
    often forms extensive forests to the exclusion of all other trees.
    In those regions along the river swamps, the trees are often
    submerged for several months of the year.

How to tell them from each other: In summer the larch may be told from
    the cypress by its leaves (compare Figs. 14 and 16). In winter the
    two can be distinguished by their characteristic forms. The larch is
    a broader tree as compared with the cypress and its form is more
    conical. The cypress is more slender and it is taller. The two have
    been grouped together in this study because they are both coniferous
    trees and, unlike the other Conifers, are both deciduous, their
    leaves falling in October.

[Illustration: FIG. 14.--Twig of the Larch in Summer.]


THE EUROPEAN LARCH (_Larix europaea_)

Distinguishing characters: Its leaves, which are needle-shaped and about
    an inch long, are borne in *clusters* close to the twig, Fig. 14.
    There are many leaves to each cluster. This characteristic together
    with the *spire-like* form of the crown will distinguish the tree at
    a glance.

Leaf: The leaves are of a light-green color but become darker in the
    spring and in October turn yellow and drop off. The cypress, which
    is described below, is another cone-bearing tree which sheds its
    leaves in winter.

[Illustration: FIG. 15.--Twig of the Larch in Winter.]

Form and size: A medium-sized tree with a conical head and a straight
    and tapering trunk. (See Fig. 90.)

Range: Central Europe and eastern and central United States.

Soil and location: Requires a deep, fresh, well-drained soil and needs
    plenty of light. It flourishes in places where our native species
    would die. Grows very rapidly.

Enemies: The larch is subject to the attacks of a _sawfly_, which has
    killed many trees of the American species. A _fungus_ (_Trametes
    pini_) which causes the tree to break down with ease is another of
    its enemies.

Value for planting: A well-formed tree for the lawn. It is also useful
    for group planting in the forest.

Commercial value: Because its wood is strong and durable the larch is
    valuable for poles, posts, railroad ties, and in shipbuilding.

[Illustration: FIG. 16.--Twig of the Cypress.]

Other characters: The _fruit_ is a small cone about one inch long,
    adhering to the tree throughout the winter.

[Illustration: FIG. 17.--The Bald Cypress.]

Comparisons: The tree is apt to be confused with the _American larch_,
    also known as _tamarack_ and _hackmatack_, but differs from it in
    having longer leaves, cones twice as large and more abundant and
    branches which are more pendulous.

    The larch differs from the bald cypress in the broader form of its
    crown and the cluster-like arrangement of its leaves. The twigs of
    the bald cypress are flat and feathery. The larch and bald cypress
    have the common characteristics of both shedding their leaves in
    winter and preferring to grow in moist or swampy soils. The larch,
    especially the native species, forms the well-known tamarack swamps
    of the north. The bald cypress grows in a similar way in groups in
    the southern swamps.


BALD CYPRESS (_Taxodium distichum_)

Distinguishing characters: The *feathery character* of the *twigs*, Fig.
    16, and the *spire-like form* of the tree, Fig. 17, which is taller
    and more slender than the larch, will distinguish this species from
    others.

[Illustration: FIG. 18.--Cypress "Knees."]

Leaf: The leaves drop off in October, though the tree is of the
    cone-bearing kind. In this respect it is like the larch.

Form and size: Tall and pyramidal.

Range: The cypress is a southern tree, but is found under cultivation in
    parks and on lawns in northern United States.

Soil and location: Grows naturally in swamps, but will also do well in
    ordinary well-drained, good soil. In its natural habitat it sends
    out special roots above water. These are known as "_cypress knees_"
    (Fig. 18) and serve to provide air to the submerged roots of the
    tree.

Enemies: None of importance.

Value for planting: An excellent tree for park and lawn planting.

Commercial value: The wood is light, soft, and easily worked. It is used
    for general construction, interior finish, railroad ties, posts and
    cooperage.

Other characters: The _bark_ is thin and scaly. The _fruit_ is a cone
    about an inch in diameter. The general _color_ of the tree is a
    dull, deep green which, however, turns orange brown in the fall.

Comparisons: The cypress and the larch are apt to be confused,
    especially in the winter, when the leaves of both have dropped. The
    cypress is more slender and is taller in form. The leaves of each
    are very different, as will be seen from the accompanying
    illustrations.



GROUP V. THE HORSECHESTNUT, ASH AND MAPLE

How to tell them from other trees: The horsechestnut, ash, and maple
    have their branches and buds arranged on their stems *opposite* each
    other as shown in Figs. 20, 22 and 24. In other trees, this
    arrangement is *alternate*, as shown in Fig. 19.

How to tell these three from each other. If the bud is large--an inch to
    an inch and a half long--dark brown, and _sticky_, it is a
    _horsechestnut_.

    If the bud is _not sticky_, much smaller, and _rusty brown to black_
    in color, and the ultimate twigs, of an olive green color, are
    _flattened_ at points below the buds, it is an _ash_.

[Illustration: FIG. 19.--Alternate Branching (Beech.)]

    If it is not a horsechestnut nor an ash and its small buds have
    many scales covering them, the specimen with branches and buds
    opposite must then be a _maple_. Each of the maples has one
    character which distinguishes it from all the other maples. For the
    sugar maple, this distinguishing character is the _sharp point of
    the bud_. For the silver maple it is the _bend in the terminal
    twig_. For the red maple it is the _smooth gray-colored bark_. For
    the Norway maple it is the _reddish brown color of the full, round
    bud_, and for the box elder it is the _greenish color of its
    terminal twig_.

    The form of the tree and the leaves are also characteristic in each
    of the maples, but for the beginner who does not wish to be burdened
    with too many of these facts at one time, those just enumerated
    will be found most certain and most easily followed.

[Illustration: FIG. 20.--Opposite Branching (Horsechestnut.)]


THE HORSECHESTNUT
(_Aesculus hippocastanum_)

Distinguishing characters: The *sticky* nature of the *terminal bud* and
    its *large size* (about an inch long). The bud is dark brown in
    color. See Fig. 20.

Leaf: Five to seven leaflets, usually seven. Fig. 21.

Form and size: Medium-sized tree, pyramidal head and coarse twigs.

Range: Europe and eastern United States.

Soil and location: Prefers a deep, rich soil.

Enemies: The leaves are the favorite food of caterpillars and are
    subject to a blight which turns them brown prematurely. The trunk is
    often attacked by a disease which causes the flow of a slimy
    substance.

Value for planting: On account of its showy flowers, the horsechestnut
    is a favorite for the park and lawn.

Commercial value: The wood is not durable and is not used commercially.

Other characters: The _flowers_ appear in large white clusters in May
    and June. The _fruit_ is large, round, and prickly.

[Illustration: FIG. 21.--Leaf of the Horsechestnut.]

Comparisons: The _red horsechestnut_ differs from this tree in having
    red flowers. The _buckeye_ is similar to the horsechestnut, but its
    bud is not sticky and is of a lighter gray color, while the leaf
    generally has only five leaflets.


THE WHITE ASH (_Fraxinus americana_)

Distinguishing characters: The terminal *twigs* of glossy olive green
    color are *flattened* below the bud. Fig. 22. The bud is
    rusty-brown.

[Illustration: FIG. 22.--Twig of White Ash.]

Leaf: Five to nine leaflets. Fig. 23.

Form and size: A large tree with a straight trunk.

Range: Eastern North America.

Soil and location: Rich, moist soil.

Enemies: In cities it is very often attacked by sucking insects.

Value for planting: The white ash grows rapidly. On account of its
    insect enemies in cities, it should be used more for forest planting
    and only occasionally for ornament.

Commercial value: It has a heavy, tough, and strong wood, which is
    valuable in the manufacture of cooperage stock, agricultural
    implements, and carriages. It is superior in value to the black ash.

Other characters: The _bark_ is gray. The _flowers_ appear in May.

Comparisons: The white ash is apt to be confused with the _black ash_
    (_Fraxinus nigra_), but differs from the latter in having a
    lighter-colored bud. The bud of the black ash is black. The bark of
    the white ash is darker in color and the terminal twigs are more
    flattened than those of the black ash.

[Illustration: FIG. 23.--Leaf of White Ash.]


SUGAR MAPLE (_Acer saccharum_)

Distinguishing characters: The *bud is sharp-pointed*, scaly, and
    reddish brown. Fig. 24.

[Illustration: FIG. 24.--Twig of the Sugar Maple.]

Leaf: Has sharp points and round sinus. Fig. 25.

Form and size: The crown is oval when the tree is young and round in old
    age. Fig. 26.

Range: Eastern United States.

Soil and location: Moist and deep soil, and cool, shady positions.

Enemies: Subject to drouth, especially in cities. Is attacked by the
    _sugar maple borer_ and the _maple phenacoccus_, a sucking insect.

Value for planting: Its rich and yellow color in the fall, and the fine
    spread of its crown make it a desirable tree for the lawn,
    especially in the country.

Commercial value: Its wood is hard and takes a good polish; used for
    interior finish and furniture. The tree is also the source of maple
    sugar. Fig. 27.

Other characters: The _bark_ is smooth in young trees and in old trees
    it shags in large plates. The _flowers_ appear in the early part of
    April.

Other common names: The sugar maple is sometimes called _rock maple_ or
    _hard maple_.


SILVER MAPLE (_Acer saccharinum_)

Distinguishing characters: The tips of the *twigs curve upwards* (Fig.
    28), the bark is scaly, and the leaves are very deeply cleft and are
    silvery on the under side.

[Illustration: FIG. 25.--Leaf of Sugar Maple.]

Leaf: Deeply cleft and silvery under side. Fig. 29.

Form and size: A large tree with the main branches separating from the
    trunk a few feet from the ground. The terminal twigs are long,
    slender, and drooping.

Range: Eastern United States.

Soil and location: Moist places.

Enemies: The _leopard moth_, a wood-boring insect, and the
    _cottony-maple scale_, a sucking insect.

[Illustration: FIG. 26.--The Sugar Maple.]

Value for planting: Grows too rapidly and is too short-lived to be
    durable.

Commercial value: Its wood is soft, weak, and little used.

Other characters: The _bark_ is light gray, smooth at first and scaly
    later on. The scales are free at each end and attached in the
    center. The _flowers_ appear before the leaves in the latter part of
    March or early April.

[Illustration: FIG. 27.--Tapping the Sugar Maple.]

Other common names: The silver maple is sometimes known as _soft maple_
    or _white maple_.


RED MAPLE (_Acer rubrum_)

[Illustration: FIG. 28.--Terminal Twig of Silver Maple.]

Distinguishing characters: The *bark is smooth and light gray*, like
    that of the beech, on the upper branches in older trees, and in
    young trees over the whole trunk. Fig. 30. The buds are in clusters,
    and the terminal twigs, Fig. 31, are quite red.

[Illustration: FIG. 29.--Leaf of the Silver Maple.]

Leaf: Whitish underneath with three-pointed lobes. Fig. 32.

Form and size: A medium-sized tree with a narrow, round head.

Range: Eastern North America.

Soil and location: Prefers moist places.

Enemies: Leaf blotches (_Rhytisma acerinum_) which, however, are not
    very injurious.

Value for planting: Suitable as a shade tree for suburban streets. Its
    rich red leaves in the fall make it attractive for the lawn.

[Illustration: FIG. 30.--Bark of the Red Maple.]

Commercial value: Its wood is heavy, close-grained, and takes a good
    polish. Used for furniture and fuel.

Other characters: The _bud_ is small, round, and red. The _flowers_
    appear before the leaves are out in the early part of April.

[Illustration: FIG. 31.--Twig of the Red Maple.]

[Illustration: FIG. 32.--Leaf of the Red Maple.]

Other common names: The red maple is sometimes known as _swamp maple_.

[Illustration: FIG. 33.--Twig of Norway Maple.]

Comparisons: The red maple is apt to be confused with the silver maple,
    but the latter can be distinguished by its turned-up twigs and scaly
    bark over the whole trunk of the tree, which presents a sharp
    contrast to the straight twig and smooth bark of the red maple. The
    latter has a bark similar to the beech, but its branches are
    _opposite_, while those of the beech are _alternate_.


NORWAY MAPLE (_Acer platanoides_)

Distinguishing characters: The bud, Fig. 33, is *oval and reddish-brown*
    in color; when taken off, a *milky juice exudes*. The bark is close.
    Fig. 34

[Illustration: FIG. 34.--Bark of Norway Maple.]

Leaf: Like the leaf of the sugar maple but thicker in texture and darker
    in color. Fig. 35.

Form and size: A tall tree with a broad, round head.

Range: Europe and the United States.

Soil and location: Will grow in poor soil.

Enemies: Very few.

Value for planting: One of the best shade trees.

Commercial value: None.

Other characters: The _bark_ is close like that of the mockernut
    hickory.

Comparisons: The Norway maple is apt to be confused with the _sycamore
    maple_ (_Acer pseudoplatanus_), but differs from the latter in
    having a reddish bud instead of a green bud, and a close bark
    instead of a scaly bark.


BOX ELDER (_Acer negundo_)

Distinguishing characters: The terminal *twigs are green*, and the buds
    are round and small. Fig. 36.

Leaf: Has three to seven leaflets.

[Illustration: FIG. 35.--Leaf of Norway Maple.]

Form and size: A medium-sized tree with a short trunk and wide-spreading
    top.

Range: Eastern United States to the Rocky Mountains.

Soil and location: Grows rapidly in deep, moist soil and river valleys,
    but accommodates itself to the dry and poor soil conditions of the
    city.

[Illustration: Figure 36.--Twig of the Box Elder.]

Enemies: Few.

Value for planting: Used as a shade tree in the Middle West, but the
    tree is so ill formed and so short-lived that it is not to be
    recommended.

Commercial value: None. The wood is soft.

Other characters: The _bark_ of the trunk is smooth and yellowish-green
    in young trees and grayish brown in older specimens. The _flowers_
    appear in the early part of April. The _fruit_ takes the form of
    yellowish-green keys which hang on the tree till late fall.

Other common names: The box elder is also commonly known as the
    _ash-leaf maple_.



GROUP VI. TREES TOLD BY THEIR FORM: ELM, POPLAR, GINGKO AND WILLOW

How to tell them from other trees: The trees described in this group are
    so distinctive in their general _form_ that they may, for the
    purpose of study, be grouped together, and distinguished from all
    other trees by this characteristic.

How to tell them from each other: The American elm is _vase-like_ in
    shape; the Lombardy poplar is narrow and _spire-like_; the gingko,
    or maidenhair tree, is _odd_ in its mode of _branching_; and the
    weeping willow is extremely _pendulous_.


AMERICAN ELM (_Ulmus americana_)

Distinguishing characters: The tree can be told at a glance by its
    general branching habit. The limbs arch out into a wide-spreading
    *fan or vase-like crown* which loses itself in numerous fine
    drooping branchlets. See Fig. 37.

[Illustration: FIG. 37.--American Elm.]

Leaf: The leaves are simple, alternate, and from 2 to 5 inches long.

[Illustration: FIG. 38.--English Elm in Winter.]

Form and size: It is a tall tree with a trunk that divides a short
    distance above ground. Its general contour, together with the
    numerous branches that interlace its massive crown, give the elm an
    interesting and stately appearance which is unequaled by any other
    tree.

[Illustration: FIG. 39.--Lombardy Poplar.]

Range: Eastern North America.

Soil and location: The elm prefers a deep, rich and moist soil, but will
    adapt itself even to the poor soil of the city street.

Enemies: _The leopard moth_, a wood-boring insect, and the _elm leaf
    beetle_, a leaf-eating insect, are the two most important enemies of
    the tree. Their ravages are very extensive.

Value for planting: The tree has a character of its own which cannot be
    duplicated for avenue or lawn planting.

Commercial value: The wood is strong and tough and therefore has a
    special value for cooperage, agricultural implements, carriages, and
    shipbuilding.

Other characters: The _buds_ are small, brown, and smooth, while those
    of the European elms are covered with down. The _small side twigs_
    come out at almost right angles to the larger terminal twigs, which
    is not the case in other species of elm.

[Illustration: FIG. 40.--Leaf of Carolina Poplar.]

Other common names: _White elm_.

Comparisons: The _English elm_ (_Ulmus campestris_) is also a tall,
    dignified tree commonly seen under cultivation in America, but may
    be told from the American species by the difference in their general
    contour. The branches of the English species spread out but do not
    arch like those of the American elm, and the bark of the English elm
    is darker and coarser, Fig. 38. Little tufts of dead twigs along the
    main branches and trunk of the tree are characteristic of the
    English elm and will frequently help to distinguish it from the
    American elm.

    The _Camperdown elm_ may be recognized readily by its dwarf size and
    its low drooping umbrella-shaped crown.


LOMBARDY OR ITALIAN POPLAR (_Populus nigra, var. italica_)

Distinguishing characters: Its *tall, slender, spire-like form* and
    rigidly *erect branches*, which commence low on the trunk, make this
    tree very distinct at all seasons of the year. See Fig. 39.

Leaf: Triangular in shape, similar to that of the Carolina poplar but
    smaller, see Fig. 40.

Range: Asia, Europe, and North America.

Soil and location: The poplar is easily grown in poor soil, in any
    location, and is very hardy.

Value for planting: The tree has a distinctive form which makes it
    valuable for special landscape effects. It is also used for shelter
    belts and screening. Like all poplars it is short lived and will
    stand pruning well.

Commercial value: None.

[Illustration: FIG. 41.--Carolina Poplar.]

Comparisons: The _Carolina poplar_, or Cottonwood (_Populus deltoides_)
    can be told from the Lombardy poplar by its wider crown and its more
    open branching, Fig. 41. It may be recognized by its big terminal
    twigs, which are light yellow in color and coarser than those of the
    Lombardy poplar, Fig. 42. Its bark is smooth, light and
    yellowish-green in young trees, and dark gray and fissured in older
    specimens. Its large, conical, glossy, chestnut-brown bud is also
    characteristic, Fig. 42. Its flowers, in the form of large catkins,
    a peculiarity of all poplars, appear in the early spring. The
    Carolina poplar is commonly planted in cities because it grows
    rapidly and is able to withstand the smoke and drouth conditions of
    the city. Where other trees, however, can be substituted with
    success, the poplar should be avoided. Its very fast growth is
    really a point against the tree, because it grows so fast that it
    becomes too tall for surrounding property, and its wood being
    extremely soft and brittle, the tree frequently breaks in
    windstorms. In many cases it is entirely uprooted, because it is not
    a deep-rooted tree. Its larger roots, which spread near the
    surface, upset the sidewalk or prevent the growth of other
    vegetation on the lawn, while its finer rootlets, in their eager
    search for moisture, penetrate and clog the joints of neighboring
    water and sewer pipes. The tree is commonly attacked by the
    _oyster-shell scale_, an insect which sucks the sap from its bark
    and which readily spreads to other more valuable trees like the elm.
    The female form of this tree is even more objectionable than the
    male, because in the early spring the former produces an abundance
    of cotton from its seeds which litters the ground and often makes
    walking dangerous. The only justification for planting the Carolina
    poplar is in places where the conditions for tree growth are so poor
    that nothing else will grow, and in those cases the tree should be
    cut back periodically in order to keep it from becoming too tall and
    scraggly. It is also desirable for screening in factory districts
    and similar situations.

[Illustration: FIG. 42.--Bud of the Carolina Poplar.]

    The _silver_ or _white poplar_ (_Populus alba_) may be told from the
    other poplars by its characteristic smooth, _whitish-green bark_,
    often spotted with dark blotches, Fig. 43. The _leaves are
    silvery-white_ and downy on the under side. The twigs are dark green
    in color and densely covered with a white down. It grows to very
    large size and forms an irregular, wide-spreading, broad head, which
    is characteristically different from that of any of the other
    poplars.

[Illustration: FIG. 43.--Bark of the Silver Poplar.]

    The _quaking aspen_ (_Populus tremuloides_), the _large-toothed
    aspen_ (_Populus grandidentata_) and the _balsam poplar_ or _balm of
    Gilead_ (_Populus balsamifera_) are other common members of the
    poplar group. The quaking aspen may be told by its reddish-brown
    twigs, narrow sharp-pointed buds, and by its small finely toothed
    leaves. The large-toothed aspen has thicker and rather downy buds
    and broader and more widely toothed leaves. The balsam poplar has a
    large bud thickly covered with a sticky, pungent, gelatinous
    substance.


GINGKO OR MAIDENHAIR TREE (_Gingko biloba_)

[Illustration: FIG. 44.--Gingko Trees.]

Distinguishing characters: The *peculiar branches* of this tree *emerge
    upward* from a straight tapering trunk *at an angle of about 45°*
    and give to the whole tree a striking, Oriental appearance, which is
    quite different from that of any other tree, Fig. 44.

Leaf: Like that of a leaflet of maidenhair fern, Fig. 45.

Range: A native of northern China and introduced into eastern North
    America.

Soil and location: The gingko will grow in poor soils.

Enemies: Practically free from insects and disease.

[Illustration: FIG. 45.--Leaves of the Gingko Tree.]

Value for planting: It makes a valuable tree for the street where heavy
    shade is not the object and forms an excellent wide-spreading
    specimen tree on the lawn.

Other characters: The _fruit_ consists of a stone covered by sweet,
    ill-smelling flesh. The tree is dioecious, there being separate male
    and female trees. The male tree is preferable for planting in order
    to avoid the disagreeable odor of the fruit which appears on the
    female trees when about thirty years old. The male tree has a
    narrower crown than the female tree. The buds (Fig. 46) are very odd
    and are conspicuous on the tree throughout the winter. The leaves of
    the gingko shed in the winter. In this respect the tree is like the
    larch and the bald cypress.

[Illustration: FIG. 46.--Bud of the Gingko Tree.]

    The gingko belongs to the yew family, which is akin to the pine
    family. It is therefore a very old tree, the remains of the forests
    of the ancient world. The gingko in its early life is tall and
    slender with its few branches close to the stem. But after a time
    the branches loosen up and form a wide-spreading crown. In the
    Orient it attains enormous proportions and in this country it also
    grows to a fairly large size when planted on the open lawn or in
    groups far apart from other trees so that it can have plenty of room
    to spread. It then produces a picturesque effect of unusual
    interest.


WEEPING WILLOW (_Salix babylonica_)

Distinguishing characters: All the willows have a single cap-like scale
    to the bud, and this species has an unusually *drooping mass of
    slender branchlets* which characterizes the tree from all others,
    Fig. 47.

[Illustration: FIG. 47.--Weeping Willow.]

Form and size: It grows to large size.

Range: Asia and Europe and naturalized in eastern United States.

Soil and location: Prefers moist places near streams and ponds.

Enemies: None of importance.

Value for planting: The weeping willow has a special ornamental effect
    in cemeteries and along lakes and river banks in parks.

Commercial value: It is used in the United States for charcoal and for
    fuel.

Comparisons: The _pussy willow_ (_Salix discolor_) may easily be told
    from the other willows by its small size; it is often no higher than
    a tall shrub. Its branches are _reddish green_ and the buds are dark
    red, smooth and glossy. The predominating color of the twigs and
    buds in the pussy willow is therefore a shade of _red_, while in the
    weeping willow it is _yellowish green_.



GROUP VII. TREES TOLD BY THEIR BARK OR TRUNK: SYCAMORE, BIRCH, BEECH,
BLUE BEECH, IRONWOOD, AND HACKBERRY

How to tell them from other trees: The _color of the bark or the form of
    the trunk_ of each of the trees in this group is distinct from that
    of any other tree.

How to tell them from each other: In the sycamore, the bark is
    _mottled_; in the white birch, it is _dull white_; in the beech, it
    is _smooth and gray_; in the hackberry, it is covered with numerous
    _corky warts_; in the blue beech, the trunk of the tree is _fluted_,
    as in Fig. 54, and in the ironwood, the bark _peels_ in thin
    perpendicular strips.

[Illustration: FIG. 48.--Bark of the Sycamore Tree.]


THE SYCAMORE OR PLANE TREE (_Platanus occidentalis_)

Distinguishing characters: The peculiar *mottled appearance* of the
    *bark* (Fig. 48) in the trunk and large branches is the striking
    character here. The bark produces this effect by shedding in large,
    thin, brittle plates. The newly exposed bark is of a yellowish green
    color which often turns nearly white later on. *Round seed balls*,
    about an inch in diameter, may be seen hanging on the tree all
    winter. In this species, the seed balls are usually solitary, while
    in the Oriental sycamore, a European tree similar to the native one,
    they appear in clusters of two, or occasionally of three or four.
    See Fig. 49.

[Illustration: FIG. 49.--Seed-balls of the Oriental Sycamore. Note one
Seed-ball cut in half.]

[Illustration: FIG. 50.--Gray or White Birch Trees.]

Leaf: The stem of the leaf completely covers the bud. This is a
    characteristic peculiar to sycamores.

Form and size: A large tree with massive trunk and branches and a broad
    head.

Range: Eastern and southern United States.

Soil and location: Prefers a deep rich soil, but will adapt itself even
    to the poor soil of the city street.

Enemies: The sycamore is frequently attacked by a fungus (_Gloeosporium
    nervisequum_), which curls up the young leaves and kills the tips of
    the branches. Late frosts also often injure its young twigs. The
    Oriental sycamore, which is the European species, is more hardy in
    these respects than the native one and is therefore often chosen as
    a substitute.

Value for planting: The Occidental sycamore is now planted very little,
    but the Oriental sycamore is used quite extensively in its place,
    especially as a shade tree. The Oriental sycamore is superior to the
    native species in many ways. It is more shapely, faster growing, and
    hardier than the native one. Both sycamores will bear transplanting
    and pruning well.

[Illustration: FIG. 51.--Bark of the Black or Sweet Birch.]

Commercial value: The wood of the sycamore is coarse-grained and hard to
    work; used occasionally for inside finishing in buildings.

Other names: _Buttonball_, _buttonwood_.

Comparisons: The _Oriental sycamore_ (_Platanus orientalis_) an
    introduced species, is apt to be confused with the Occidental
    sycamore, but may be told from the latter by the number of seed
    balls suspended from the tree. In the case of the Oriental species,
    the seed balls hang in _pairs_ or (rarely) three or four together.
    In the Occidental, the seed balls are generally _solitary_ and very
    rarely in pairs.


GRAY OR WHITE BIRCH (_Betula populifolia_)

Distinguishing characters: The *dull-white color of the bark* on the
    trunk and the _dark triangular patches below the insertion of the
    branches_ distinguish this tree; see Fig. 50. The bark of the young
    trunks and branches is reddish-brown in color and glossy. The bark
    adheres closely to the trunk of the tree and does not peel in loose,
    shaggy strips, as in the case of the yellow or golden birch. It is
    marked by small raised horizontal lines which are the lenticels or
    breathing pores. These lenticels are characteristic of all birch and
    cherry trees. In addition to the distinction in the color of the
    bark, an important character which distinguishes the gray birch from
    all other species of birch, is found in the *terminal twigs*, which
    are *rough* to the touch.

Form and size: A small tree. Frequently grows in clumps.

Range: Eastern United States.

Soil and location: The gray birch does best in a deep, rich soil, but
    will also grow in poor soils.

Enemies: The _bronze-birch borer_, a wood-destroying insect, and
    _Polyporus betulinus_, a fungus, are its chief enemies.

Value for planting: Its graceful habit and attractive bark gives the
    tree an important place in ornamental planting. It may be used to
    advantage with evergreens, and produces a charming effect when
    planted by itself in clumps.

[Illustration: FIG. 52.--Bark of the Beech.]

[Illustration: FIG. 53.--Buds of the Beech Tree.]

Commercial value: The wood is soft and not durable. It is used in the
    manufacture of small articles and for wood pulp.

Other characters: The _fruit is a catkin_.

Comparisons: The _paper birch_ (_Betula papyrifera_) is apt to be
    confused with the gray birch, because both have a white bark. The
    bark of the paper birch, however, is a clear white and peels off in
    thin papery layers instead of being close. It very seldom shows any
    dark triangular markings on the trunk. Its terminal twigs are not
    rough and its trunk is usually straighter and freer from branches.

    The _black_ or _sweet birch_ (_Betula lenta_) has a bark similar to
    the gray birch, except that its color is dark gray. See Fig. 51. The
    twigs have an aromatic taste.

[Illustration: FIG. 54.--Trunk of Blue Beech.]

[Illustration: FIG. 55.--Bark of the Ironwood.]

    The _yellow birch_ (_Betula lutea_) has a yellowish or golden bark
    which constantly peels in thin, ragged, horizontal films.

    The _European white birch_ (_Betula alba_) has a dull-white bark
    like the native white birch, but has smooth terminal twigs instead
    of rough ones. It is commonly seen in the United States on lawns and
    in parks.


AMERICAN BEECH (_Fagus americana_)

Distinguishing characters: The *close-fitting, smooth, gray bark* will
    tell this tree from all others except the red maple and yellow-wood.
    See Fig. 52. The red maple may then be easily eliminated by noting
    whether the branches are alternate or opposite. They are alternate
    in the beech and opposite in the maple. The yellow-wood may be
    eliminated by noting the size of the bud. The *bud* in the
    yellow-wood is hardly noticeable and of a golden yellow color, while
    that of the beech is very *long, slender, and sharp-pointed*, and
    chestnut brown in color. See Fig. 53.

Form and size: It grows tall in the woods, but on the open lawn spreads
    out into a massive, round-headed tree.

Range: Eastern Canada and United States.

Soil and location: Prefers a rich, well-drained soil, but will grow in
    any good soil.

Enemies: _Aphides_ or plant lice that suck the sap from the leaves in
    spring and early summer are the chief enemies of the tree.

Value for planting: The pleasing color of its bark, its fine spread of
    branches, which gracefully droop down to the ground, and its
    autumnal coloring, make the beech a favorite for lawn and park
    planting. The several European species of beech are equally
    charming.

[Illustration: FIG. 56.--Bark of the Hackberry.]

Commercial value: The wood is strong, close-grained, and tough. It is
    used mainly for cooperage, tool handles, shoe lasts, chairs, etc.,
    and for fuel.

Other characters: The _fruit_ is a prickly burr encasing a sharply
    triangular nut which is sweet and edible.

Comparisons: The _European beech_ (_Fagus sylvatica_), and its weeping,
    purple-leaved, and fern-leaved varieties, are frequently met with in
    parks and may be told from the native species by its darker bark.
    The weeping form may, of course, be told readily by its drooping
    branches. The leaves of the European beeches are broader and less
    serrated than those of the American beech.


BLUE BEECH OR HORNBEAM (_Carpinus caroliniana_)

Distinguishing characters: The *fluted* or muscular effect of its
    *trunk* will distinguish the tree at a glance, Fig. 54.

Leaf: Doubly serrated; otherwise the same as that of ironwood.

Form and size: A low-spreading tree with branches arching out at various
    angles, forming a flattened head with a fine, slender spray.

Range: Very common in the eastern United States.

Soil and location: Grows in low wet woods.

Enemies: None of importance.

Value for planting: Its artistic branching and curious trunk give the
    tree an important place in park planting.

Commercial value: None.

Other characters: The bark is smooth and bluish gray in color.

Comparisons: The blue beech or hornbeam is often confused with the
    _ironwood_ or _hop hornbeam_ (_Ostrya virginiana_). The ironwood,
    however, has a characteristic bark that peels in perpendicular,
    short, thin segments, often loose at the ends. See Fig. 55. This is
    entirely different from the close, smooth, and fluted bark of the
    blue beech. The color of the bark in the ironwood is brownish, while
    that of the blue beech is bluish-gray. The buds of the ironwood are
    greenish with brown tips, while the bud of the blue beech shows no
    green whatever.


HACKBERRY (_Celtis occidentalis_)

Distinguishing characters: The tree may be told readily from other trees
    by the *corky tubercles* on the bark of the lower portion of the
    trunk. See Fig. 56.

Leaf: Has three predominating veins and is a bit more developed on one
    side than on the other.

Form and size: A small or medium-sized tree with a single stem and broad
    conical crown.

Range: United States and Canada.

Soil and location: Grows naturally in fertile soils, but will adapt
    itself to almost sterile soils as well.

Enemies: The hackberry is usually free from disease, though often its
    leaves are covered with insect galls.

Value for planting: It is extensively planted as a shade tree in the
    Middle West, and is frequently seen as an ornamental tree in the
    East.

Commercial value: It has little economic value except for fuel.

Other characters: The _fruit_ is berry-like, with a hard pit. The fleshy
    outer part is sweet.

Other common names: _Nettle tree_; _sugarberry_.



GROUP VIII. THE OAKS AND CHESTNUT

How to tell them from other trees: The oaks are rather difficult to
    identify and, in studying them it will often be necessary to look
    for more than one distinguishing character. The oaks differ from
    other trees in bearing _acorns_. Their _leaves_ have many lobes and
    their upper lateral _buds_ cluster at the top of the twigs. The
    general contour of each oak presents a characteristic branching and
    sturdiness uncommon in other trees.

    The chestnut differs from other trees in bearing _burs_ and its
    _bark_ is also distinctly characteristic.

How to tell them from each other: There are two groups of oaks, the
    _white oak_ and the _black oak_. The white oaks mature their acorns
    in one year and, therefore, only acorns of the same year can be
    found on trees of this group. The black oaks take two years in which
    to mature their acorns and, therefore, young acorns of the present
    year and mature acorns of the previous year may be found on the same
    tree at one time. The _leaves_ of the white oaks have rounded
    margins and rounded lobes as in Fig. 57, while those of the black
    oaks have pointed margins and sharp pointed lobes as shown in Figs.
    60, 62 and 64. The _bark_ of the white oaks is light colored and
    breaks up in loose flakes as in Fig. 58, while that of the black
    oaks is darker and deeply ridged or tight as in Figs. 59 and 61. The
    white oak is the type of the white oak group and the black, red and
    pin oaks are types of the other. For the characterization of the
    individual species, the reader is referred to the following pages.

[Illustration: FIG. 57.--Leaf and Fruit of White Oak. (Quercus alba.)]


WHITE OAK (_Quercus alba_)

Distinguishing characters: The massive ramification of its branches is
    characteristic of this species and often an easy clue to its
    identification. The *bark* has a *light gray color*--lighter than
    that of the other oaks--and breaks into soft, loose flakes as in
    Fig. 58. The *leaves are deeply lobed* as in Fig. 57. The *buds are
    small, round and congested* at the end of the year's growth. The
    acorns usually have no stalks and are set in shallow, rough cups.
    The kernels of the acorns are white and palatable.

Form and size: The white oak grows into a large tree with a
    wide-spreading, massive crown, dissolving into long, heavy, twisted
    branches. When grown in the open it possesses a short sturdy trunk;
    in the forest its trunk is tall and stout.

Range: Eastern North America.

[Illustration: FIG. 58.--Bark of White Oak. (Quercus alba.)]

Soil and location: The white oak thrives in almost any well-drained,
    good, deep soil except in a very cold and wet soil. It requires
    plenty of light and attains great age.

Enemies: The tree is comparatively free from insects and disease except
    in districts where the Gipsy moth is common, in which case the
    leaves of the white oak are a favorite food of its caterpillars.

[Illustration: FIG. 59.--Bark of Black Oak. (Quercus velutina).]

Value for planting: The white oak is one of the most stately trees. Its
    massive form and its longevity make the tree suitable for both lawn
    and woodland planting but it is not used much because it is
    difficult to transplant and grows rather slowly.

Commercial value: The wood is of great economic importance. It is heavy,
    hard, strong and durable and is used in cooperage, construction
    work, interior finish of buildings and for railroad ties, furniture,
    agricultural implements and fuel.

Comparisons: The _swamp white oak_ (_Quercus platanoides_) is similar to
    the white oak in general appearance of the bark and form and is
    therefore liable to be confused with it. It differs from the white
    oak, however, in possessing a more straggly habit and in the fact
    that the bark on the under side of its branches shags in loose,
    large scales. Its buds are smaller, lighter colored and more downy
    and its acorns are more pointed and with cups more shallow than
    those of the white oak. The tree also grows in moister ground,
    generally bordering swamps.

[Illustration: FIG. 60.--Leaf and Fruit of Black Oak. (Quercus
velutina).]


BLACK OAK (_Quercus velutina_)

Distinguishing characters: The *bark* is black, rough and cut up into
    firm *ridges* especially at the base of the tree, see Fig. 59. The
    _inner bark_ has a _bright yellow color_: the *leaves* have _sharp
    points_ and are wider at the base than at the tip as shown in Fig.
    60. The buds are _large, downy_ and _sharp pointed_. The acorns are
    small and have deep, scaly cups the inner margins of which are
    downy. The kernels are yellow and bitter.

Form and size: The tree grows in an irregular form to large size, with
    its branches rather slender as compared with the white oak and with
    a more open and narrow crown.

Range: Eastern North America.

Soil and location: It will grow in poor soils but does best where the
    soil is rich and well drained.

Enemies: None of importance.

Value for planting: The black oak is the poorest of the oaks for
    planting and is rarely offered by nurserymen.

Commercial value: The wood is heavy, hard and strong, but checks readily
    and is coarse grained. It is of little value except for fuel. The
    bark is used for tannin.

Other common names: _Yellow oak_.

Comparisons: The black oak might sometimes be confused with the _red_
    and _scarlet oaks_. The yellow, bitter inner bark will distinguish
    the black oak from the other two. The light-colored, smooth bark of
    the red oak and the dark, ridged bark of the black oak will
    distinguish the two, while the bark of the scarlet oak has an
    appearance intermediate between the two. The buds of the three
    species also show marked differences. The buds of the black oak are
    covered with hairs, those of the scarlet oak have fewer hairs and
    those of the red are practically free from hairs. The leaves of each
    of the three species are distinct and the growth habits are
    different.


RED OAK (_Quercus rubra_)

Distinguishing characters: The *bark* is perpendicularly fissured into
    long, _smooth, light gray strips_ giving the trunk a characteristic
    *pillar effect* as in Figs. 61 and 94. It has the straightest trunk
    of all the oaks. The leaves possess _more lobes_ than the leaves of
    any of the other species of the black oak group, see Fig. 62. The
    acorns, the largest among the oaks, are semispherical with the cups
    extremely shallow. The buds are large and sharp pointed, but not as
    large as those of the black oak. They also have a few fine hairs on
    their scales, but are not nearly as downy as those of the Black oak.

[Illustration: FIG. 61--Bark of Red Oak.]

Form and size: The red oak is the largest of the oaks and among the
    largest of the trees in the northern forests. It has a straight
    trunk, free from branches to a higher point than in the white oak,
    see Fig. 94. The branches are less twisted and emerge at sharper
    angles than do those of the white oak.

Range: It grows all over Eastern North America and reaches north farther
    than any of the other oaks.

Soil and location: It is less fastidious in its soil and moisture
    requirements than the other oaks and therefore grows in a great
    variety of soils. It requires plenty of light.

[Illustration: FIG. 62.--Leaf and Fruit of Red Oak.]

Enemies: Like most of the other oaks, this species is comparatively free
    from insects and disease.

Value for planting: The red oak grows faster and adapts itself better to
    poor soil conditions than any of the other oaks and is therefore
    easy to plant and easy to find in the nurseries. It makes an
    excellent street tree, is equally desirable for the lawn and is
    hardly surpassed for woodland planting.

Commercial value: The wood is hard and strong but coarse grained, and is
    used for construction timber, interior finish and furniture. It is
    inferior to white oak where strength and durability are required.


PIN OAK (_Quercus palustris_)

Distinguishing characters: Its method of *branching* will characterize
    the tree at a glance. It develops a well-defined _main_ ascending
    _stem_ with numerous _drooping_ side _branches_ as in Fig. 63. The
    buds are very small and sharp pointed and the leaves are small as in
    Fig. 64. The bark is dark, firm, smooth and in close ridges. The
    acorn is small and carries a light brown, striped nut, wider than
    long and bitter. The cup is shallow, enclosing only the base of the
    nut.

[Illustration: FIG. 63.--Pin Oaks in Winter.]

Form and size: The pin oak is a medium-sized tree in comparison with
    other oaks. It develops a tall, straight trunk that tapers
    continuously through a pyramidal crown of low, drooping tender,
    branches.

Range: Eastern North America.

Soil and location: It requires a deep, rich, moist soil and grows
    naturally near swamps. Its roots are deep and spreading. The tree
    grows rapidly and is easily transplanted.

Enemies: None of importance.

Value for planting: The pin oak is an extremely graceful tree and is
    therefore extensively used for planting on lawns and on certain
    streets where the tree can find plenty of water and where conditions
    will permit its branches to droop low.

Commercial value: The wood is heavy and hard but coarse grained and
    liable to check and warp. Its principal use is in the construction
    of houses and for shingles.

[Illustration: FIG. 64.--Leaf and Fruit of Pin Oak.]


CHESTNUT (_Castanea dentata_)

Distinguishing characters: The *bark* in young trees is smooth and of a
    marked reddish-bronze color, but when the tree grows older, the bark
    breaks up into *diamond-shaped ridges*, sufficiently characteristic
    to distinguish the tree at a glance, see Fig. 65. A close
    examination of the _terminal twig_ will show _three ridges_ and _two
    grooves_ running down along the stem from the base of each leaf or
    leaf-scar. The twig has no true terminal bud. The fruit, a large,
    round *bur*, prickly without and hairy within and enclosing the
    familiar dark brown, sweet edible nuts is also a distinguishing mark
    of the tree.

Leaf: The leaves are distinctly long and narrow. They are from 6 to 8
    inches long.

Form and size: The chestnut is a large tree with a massive trunk and
    broad spreading crown. The chestnut tree when cut, sprouts readily
    from the stump and therefore in places where the trees have once
    been cut, a group of two to six trees may be seen emerging from the
    old stump.

[Illustration: FIG. 65.--Trunk of Chestnut Tree.]

Range: Eastern United States.

Soil and location: It will grow on rocky as well as on fertile soils and
    requires plenty of light.

Enemies: During the past nine years nearly all the chestnut trees in the
    United States have been attacked by a fungus disease (_Diaporthe
    parasitica_, Mur.) which still threatens the entire extinction of
    the chestnut trees in this country. No remedy has been discovered
    and all affected trees should be cut down and the wood utilized
    before it decays and becomes worthless. No species of chestnut tree
    is entirely immune from this disease, though some species are highly
    resistant.

Value for planting: The chestnut is one of the most rapidly growing
    hardwood trees but, on account of its disease, which is now
    prevalent everywhere, it is not wise to plant chestnut trees for the
    present.

Commercial value: The wood is light, not very strong and liable to warp.
    It is durable when brought in contact with the soil and is therefore
    used for railroad ties, fence-posts, poles, and mine timbers. It is
    also valuable for interior finish in houses and for fuel. Its bark
    is used in the manufacture of tanning extracts and the nuts are sold
    in cities in large quantities.




CHAPTER III

HOW TO IDENTIFY TREES--(Continued)



GROUP IX. THE HICKORIES, WALNUT AND BUTTERNUT

How to tell them from other trees and from each other: The hickory
    trees, though symmetrical, have a rugged _appearance_ and the
    _branches_ are so sturdy and black as to give a special distinction
    to this group. The _buds_ are different from the buds of all other
    trees and sufficiently characteristic to distinguish the various
    species of the group. The _bark_ is also a distinguishing character.

    The walnut and butternut have _chambered piths_ which distinguish
    them from all other trees and from each other.


SHAGBARK HICKORY (_Hicoria ovata_)

Distinguishing characters: The yellowish brown *buds* nearly as large as
    those of the mockernut hickory, _are each provided with two long,
    dark, outer scales_ which stand out very conspicuously as shown in
    Fig. 67. The *bark* in older specimens *shags* off in rough strips,
    sometimes more than a foot long, as shown in Fig. 68. These two
    characters will readily distinguish the tree at all seasons of the
    year.

[Illustration: FIG. 66.--A Shagbark Hickory Tree.]

Leaf: The leaf is compound, consisting of 5 or 7 leaflets, the terminal
    one generally larger.

Form and size: A tall, stately tree--the tallest of the hickories--of
    rugged form and fine symmetry, see Fig. 66.

Range: Eastern North America.

Soil and location: The shagbark hickory grows in a great variety of
    soils, but prefers a deep and rather moist soil.

Enemies: The _hickory bark borer_ (_Scolytus quadrispinosus_) is its
    principal enemy. The insect is now killing thousands of hickory
    trees in the vicinity of New York City and on several occasions has
    made its appearance in large numbers in other parts of the country.

Value for planting: It is difficult to transplant, grows slowly and is
    seldom found in nurseries.

[Illustration: FIG. 67.--Bud of the Shagbark Hickory.]

Commercial value: The wood is extremely tough and hard and is used for
    agricultural implements and for the manufacture of wagons. It is
    excellent for fuel and the nuts are of great value as a food.

Other characters: The fruit is a nut covered by a thick husk that
    separates into 4 or 5 segments. The kernel is sweet.

Other common names: _Shellbark hickory_.


MOCKERNUT HICKORY (_Hicoria alba_)

[Illustration: FIG. 68.--Bark of the Shagbark Hickory.]

Distinguishing characters: The *bud* is the largest among the
    hickories--nearly half an inch long--is hard and oval and covered
    with _yellowish brown_ downy _scales_ which _do not project_ like
    those of the shagbark hickory, see Fig. 69. The twigs are extremely
    coarse. The *bark* is very tight on the trunk and branches and has a
    _close_, hard, _wavy_ appearance as in Fig. 70.

Leaf: The leaf consists of 5, 7 or 9 leaflets all of which are large and
    pubescent and possess a distinct resinous odor.

Form and size: A tall tree with a broad spreading head.

Range: Eastern North America.

Soil and location: The mockernut hickory grows on a great variety of
    soils, but prefers one which is rich and well-drained.

Enemies: The same as for the shagbark hickory.

Value for planting: It is not commonly planted.

Commercial value: The wood is similar to that of the shagbark hickory
    and is put to the same uses.

Other characters: The fruit is a nut, larger and covered with a shell
    thicker than that of the shagbark. The husk is also thicker and
    separates into four segments nearly to the base. The kernel is small
    and sweet.

Other common names: _Bigbud hickory_; _whiteheart hickory_.

Comparisons: The _pignut hickory_ (_Hicoria glabra_), sometimes called
    broom hickory or brown hickory, often has a shaggy bark, but differs
    from both the shagbark and the mockernut hickory in possessing buds
    very much smaller, twigs more slender and leaflets fewer. The nut
    has a thinner husk which does not separate into four or five
    segments. The tree prefers drier ground than the other hickories.

[Illustration: FIG. 69.--Bud of the Mockernut Hickory.]

    The _bitternut_ (_Hicoria minima_) can be told from the mockernut
    and other species of hickory by its bud, which has no scales at all.
    The color of its bud is a characteristic orange yellow. The bark is
    of a lighter shade than the bark of the mockernut hickory and the
    leaflets are more numerous than in any of the hickories, varying
    from 7 to 11. Its nuts are bitter.


BLACK WALNUT (_Juglans nigra_)

Distinguishing characters: By cutting a twig lengthwise, it will be seen
    that its *pith* is divided into little _chambers_ as shown in Fig.
    71. The bud is dark gray and satiny. The bark is dark brown and
    deeply ridged and the fruit is the familiar round walnut.

[Illustration: FIG. 70.--Bark of the Mockernut Hickory.]

Form and size: A tall tree with a spreading crown composed of stout
    branches. In the open it grows very symmetrically.

Range: Eastern United States.

Soil and location: The black walnut prefers a deep, rich, fertile soil
    and requires a great deal of light.

Enemies: The tree is a favorite of many caterpillars.

Value for planting: It forms a beautiful spreading tree on open ground,
    but is not planted to any extent because it is hard to transplant.
    It grows slowly unless the soil is very deep and rich, develops its
    leaves late in the spring and sheds them early in the fall and
    produces its fruit in great profusion.

Commercial value: The wood is heavy, strong, of chocolate brown color
    and capable of taking a fine polish. It is used for cabinet making
    and interior finish of houses. The older the tree, usually, the
    better the wood, and the consumption of the species in the past has
    been so heavy that it is becoming rare. The European varieties which
    are frequently planted in America as substitutes for the native
    species yield better nuts, but the American species produces better
    wood.

[Illustration: FIG. 71.--Twig of the Black Walnut. Note the large
chambers in the pith.]

[Illustration: FIG. 72.--Twig of the Butternut. Note the small chambers
in the pith.]

Other characters: The _fruit_ is a large round nut about two inches in
    diameter, covered with a smooth husk which at first is dull green
    in color and later turns brown. The husk does not separate into
    sections. The kernel is edible and produces an oil of commercial
    value.

    The _leaves_ are compound and alternate with 15 to 23 leaflets to
    each.

Comparisons: The _butternut_ (_Juglans cinerea_) is another tree that
    has the pith divided into little chambers, but the little chambers
    here are shorter than in the black walnut, as may be seen from a
    comparison of Figs. 71 and 72. The bark of the butternut is light
    gray while that of the black walnut is dark. The buds in the
    butternut are longer than those of the black walnut and are light
    brown instead of gray in color. The form of the tree is low and
    spreading as compared with the black walnut. The fruit in the
    butternut is elongated while that of the black walnut is round. The
    leaves of the butternut have fewer leaflets and these are lighter in
    color.



GROUP X. TULIP TREE, SWEET GUM, LINDEN, MAGNOLIA, LOCUST, CATALPA,
DOGWOOD, MULBERRY AND OSAGE ORANGE


TULIP TREE (_Liriodendron tulipifera_)

Distinguishing characters: There are four characters that stand out
    conspicuously in the tulip tree--the *bud*, the *trunk*, the
    persistent *fruit cups* and the wedged *leaf*.

    The bud, Fig. 74, about three-quarters of an inch long, is covered
    by two purplish scales which lend special significance to its whole
    appearance. The trunk is extremely individual because it rises stout
    and shaft-like, away above the ground without a branch as shown in
    Fig. 73. The tree flowers in the latter part of May but the cup that
    holds the fruit persists throughout the winter. The leaf, Fig. 75,
    has four lobes, is nearly as broad as it is long and so notched at
    the upper end that it looks different from any other leaf.

[Illustration: FIG. 73.--The Tulip Tree.]

[Illustration: FIG. 74.--Bud of the Tulip Tree.]

Form and size: The tulip tree is one of the largest, stateliest and
    tallest of our trees.

Range: Eastern United States.

Soil and location: Requires a deep, moist soil.

Enemies: Comparatively free from insects and disease.

Value for planting: The tree has great value as a specimen on the lawn
    but is undesirable as a street tree because it requires considerable
    moisture and transplants with difficulty. It should be planted while
    young and where it can obtain plenty of light. It grows rapidly.

Commercial value: The wood is commercially known as _whitewood_ and
    _yellow poplar_. It is light, soft, not strong and easily worked. It
    is used in construction, for interior finish of houses, woodenware
    and shingles. It has a medicinal value.

Other characters: The _flower_, shown in Fig. 75, is greenish yellow in
    color, appears in May and resembles a tulip; hence the name tulip
    tree. The _fruit_ is a cone.

Other common names: _Whitewood_; _yellow poplar_; _poplar_ and _tulip
    poplar_.


SWEET GUM (_Liquidambar styraciflua_)

[Illustration: FIG. 75.--Leaf and Flower of the Tulip Tree.]

Distinguishing characters: The _persistent, spiny_, long-stemmed round
    *fruit*; _the corky growths on the_ *twigs*, the characteristic
    _star-shaped_ *leaves* (Fig. 76) and the very shiny greenish brown
    buds and the perfect symmetry of the tree are the chief characters
    by which to identify the species.

Form and size: The sweet gum has a beautiful symmetrical shape, forming
    a true monopodium.

[Illustration: FIG. 76.--Leaf and Fruit of the Sweet Gum. Note the corky
ridges along the twig.]

Range: From Connecticut to Florida and west to Missouri.

Soil and location: Grows in any good soil but prefers low wet ground. It
    grows rapidly and needs plenty of light.

Enemies: Is very often a favorite of leaf-eating caterpillars.

Value for planting: The tree is sought for the brilliant color of its
    foliage in the fall, and is suitable for planting both on the lawn
    and street. In growing the tree for ornamental purposes it is
    important that it should be frequently transplanted in the nursery
    and that it be transported with burlap wrapping around its roots.

Commercial value: The wood is reddish brown in color, tends to splinter
    and is inclined to warp in drying. It is used in cooperage, veneer
    work and for interior finish.

Other characters: On the smaller branches there are irregular
    developments of cork as shown in Fig. 76, projecting in some cases
    to half an inch in thickness.

Other common names: _Red gum_.

Comparisons: The _cork elm_ is another tree that possesses corky ridges
    along its twigs, but this differs from the sweet gum in wanting the
    spiny fruit and its other distinctive traits.


AMERICAN LINDEN (_Tilia Americana_)

[Illustration: FIG. 77.--Bud of the Linden Tree.]

Distinguishing characters: The great distinguishing feature of any
    linden is the *one-sided* character of its *bud* and *leaf*. The
    bud, dark red and conical, carries a sort of protuberance which
    makes it extremely one sided as shown in Fig. 77. The leaf, Fig. 78,
    is heart-shaped with the side nearest the branch largest.

[Illustration: FIG. 78.--Leaves and Flowers of the European Linden.]

Form and size: The American Linden is a medium-sized tree with a broad
    round head.

Range: Eastern North America and more common in the north than in the
    south.

Soil and location: Requires a rich, moist soil.

[Illustration: FIG. 79.--European Linden Tree.]

[Illustration: FIG. 80.--Bud of the Umbrella Tree.]

Enemies: Its leaves are a favorite food of caterpillars and its wood is
    frequently attacked by a boring insect known as the _linden borer_
    (_Saperda vestita_).

Value for planting: The linden is easily transplanted and grows rapidly.
It is used for lawn and street planting but is less desirable for these
purposes than the European species.

Commercial value: The wood is light and soft and used for paper pulp,
    woodenware, cooperage and furniture. The tree is a favorite with bee
    keepers on account of the large quantities of nectar contained in
    its flowers.

Other characters: The _fruit_ is like a pea, gray and woody. The
    _flowers_ appear in early July, are greenish-yellow and very
    fragrant.

Other common names: _Bass-wood_; _lime-tree_; _whitewood_.

Comparisons: The _European lindens_, Fig. 79, of which there are several
    species under cultivation, differ from the native species in having
    buds and leaves smaller in size, more numerous and darker in color.


THE MAGNOLIAS

The various species of magnolia trees are readily distinguished by their
buds. They all prefer moist, rich soil and have their principal value as
decorative trees on the lawn. They are distinctly southern trees; some
species under cultivation in the United States come from Asia, but the
two most commonly grown in the Eastern States are the cucumber tree and
the umbrella tree.

[Illustration: FIG. 81.--Bark of the Black Locust.]


CUCUMBER TREE (_Magnolia acuminata_)

Distinguishing characters: The *buds* are _small_ and _slender_ compared
    with those of the other magnolia trees and are _covered_ with small
    silvery silky _hairs_. The *habit* of the tree is to form a straight
    axis of great height with a symmetrical mass of branches, producing
    a perfect monopodial crown. The tree is sometimes known as _mountain
    magnolia_.


UMBRELLA TREE (_Magnolia tripetala_)

Distinguishing characters: The _buds_, Fig. 80, are extremely _long_,
    often one and a half inches, have a _purple color_ and _are smooth_.
    The tree does not grow to large size and produces an open spreading
    head. Its leaves, twelve to eighteen inches long, are larger than
    those of the other magnolia trees. The tree is sometimes called
    _elkwood_.


BLACK LOCUST (_Robinia pseudacacia_)

Distinguishing characters: The *bark* of the trunk is _rough_ and
    _deeply ridged_, as shown in Fig. 81. The *buds* are _hardly
    noticeable_; the twigs sometimes bear small spines on one side. The
    leaves are large, compound, and fern-like. The individual leaflets
    are small and delicate.

Form and size: The locust is a medium-sized tree developing a slender
    straight trunk when grown alongside of others; see Fig. 82.

Range: Canada and United States.

Soil and location: The locust will grow on almost any soil except a wet,
    heavy one. It requires plenty of light.

Enemies: The _locust borer_ has done serious damage to this tree. The
    grubs of this insect burrow in the sapwood and kill the tree or make
    it unfit for commercial use. The _locust miner_ is a beetle which is
    now annually defoliating trees of this species in large numbers.

Value for planting: It has little value for ornamental planting.

Commercial value: Though short-lived, the locust grows very rapidly. It
    is extremely durable in contact with the soil and possesses great
    strength. It is therefore extensively grown for fence-posts and
    railroad ties. Locust posts will last from fifteen to twenty years.
    The wood is valuable for fuel.

[Illustration: FIG. 82.--Black Locust Trees.]

Other characters: The _flowers_ are showy pea-shaped panicles appearing
    in May and June. The _fruit_ is a small pod.

Other common names: _Yellow locust_; _common locust_; _locust_.

Comparisons: The _honey locust_ (_Gleditsia triacanthos_) can be told
    from the black locust by the differences in their bark. In the honey
    locust the bark is not ridged, has a sort of dark iron-gray color
    and is often covered with clusters of stout, sharp-pointed thorns as
    in Fig. 83. The fruit is a large pod often remaining on the tree
    through the winter. This tree has an ornamental, but no commercial
    value.

[Illustration: FIG. 83.--Bark of the Honey Locust.]


HARDY CATALPA (_Catalpa speciosa_)

Distinguishing characters: The tree may be told by its *fruit*, which
    hang in long slender pods all winter. The leaf-scars appear on the
    stem in whorls of three and rarely opposite each other.

Form and size: The catalpa has a short, thick and twisted trunk with an
    irregular head.

Range: Central and eastern United States.

[Illustration: FIG. 84.--Hardy Catalpa Trees.]

[Illustration: FIG. 85.--Bark of the Flowering Dogwood.]

Soil and location: It grows naturally on low bottom-lands but will also
    do well in poor, dry soils.

Enemies: Practically free from disease and insects.

Value for planting: The catalpa grows very rapidly and is cultivated in
    parks for ornament and in groves for commercial purposes. The _hardy
    catalpa_ is preferable to the _common catalpa_ for planting.

Commercial value: The wood is extremely durable in contact with the soil
    and is consequently used for posts and railroad ties.

Other characters: The _flowers_, which appear in late June and early
    July, are large, white and very showy.

Other common names: _Indian bean_; _western catalpa_.

Comparisons: The _white flowering dogwood_ (_Cornus florida_) is a small
    tree which also has its leaves in whorls of three or sometimes
    opposite. It can be readily told from other trees, however, by the
    small square plates into which the outer bark on the trunk divides
    itself, see Fig. 85, and by the characteristic drooping character of
    its branches. It is one of the most common plants in our eastern
    deciduous forests. It is extremely beautiful both in the spring and
    in the fall and is frequently planted for ornament. There are many
    varieties of dogwood in common use.


WHITE MULBERRY (_Morus alba_)

A small tree recognized by its _small round reddish brown buds_ and
_light brown, finely furrowed_ (wavy looking) _bark_.

The tree, probably a native of China, is grown under cultivation in
eastern Canada and United States. It grows rapidly in moist soil and is
not fastidious in its light requirements. Its chief value is for
screening and for underplanting in woodlands.

The _red mulberry_ (_Morus rubra_) is apt to be confused with the white
mulberry, but differs in the following characters: The leaves of the red
mulberry are rough on the upper side and downy on the under side,
whereas the leaves of the white mulberry are smooth and shiny. The buds
in the red are larger and more shiny than those of the white.

The _Osage orange_ (_Toxylon pomiferum_) is similar to the mulberry in
the light, golden color of its bark, but differs from it in possessing
conspicuous spines along the twigs and branches and a more ridged bark.




CHAPTER IV


THE STRUCTURE AND REQUIREMENTS OF TREES

To be able fully to appreciate trees, their mode of life,
their enemies and their care, one must know something of
their structure and life requirements.

Structure of trees: Among the lower forms of plants there is very little
    distinction between the various parts--no differentiation into root,
    stem, or crown. Often the lower forms of animal and vegetable life
    are so similar that one cannot discriminate between them. But as we
    ascend in the scale, the various plant forms become more and more
    complex until we reach the tree, which is the largest and highest
    form of all plants. The tree is a living organism composed of cells
    like any other living organism. It has many parts, every one of
    which has a definite purpose. The three principal parts are: the
    stem, the crown, and the root.

  The stem: If we examine the cross-section of a tree, Fig. 86, we will
    notice that it is made up of numerous rings arranged in sections of
    different color and structure. The central part is known as the
    _pith_. Around the pith comes a dark, close-grained series of rings
    known as the _heartwood_, and outside the heartwood comes a lighter
    layer, the _sapwood_. The _cambium layer_ surrounds the sapwood and
    the _bark_ covers all. The cambium layer is the most important
    tissue of the tree and, together with part of the sapwood,
    transports the water and food of the tree. It is for this reason
    that a tree may be hollow, without heart and sapwood, and still
    produce foliage and fruit.

[Illustration: FIG. 86.--The Cross-Section of a Tree.]

  The crown: The crown varies in form in different species and is
    developed by the growth of new shoots from buds. The bud grows out
    to a certain length and forms the branch. Afterwards it thickens
    only and does not increase in length. New branches will then form
    from other buds on the same branch. This explains in part the
    characteristic branching of trees, Fig. 87.

[Illustration: FIG. 87.--Characteristic Form and Branching of Trees.
The trees in the photograph are pin oaks.]

    The leaves are the stomach and lungs of the tree. Their broad
    blades are a device to catch the sunlight which is needed in the
    process of digesting the food of the tree. The leaves are arranged
    on the twigs in such a way as to catch the most sunlight. The leaves
    take up the carbonic acid gas from the air, decompose it under the
    influence of light and combine it with the minerals and water
    brought up by the roots from the soil. The resulting chemical
    combinations are the sugars and starches used by the cambium layer
    in building up the body of the tree. A green pigment, _chlorophyll_,
    in the leaf is the medium by which, with the aid of sunlight, the
    sugars are manufactured.

[Illustration: FIG. 88.--Roots of a Hemlock Tree in their Search for
Water.]

    The chlorophyll gives the leaf its green color, and this explains
    why a tree pales when it is in a dying condition or when its life
    processes are interfered with. The other colors of the leaf--the
    reds, browns and yellows of the fall or spring--are due to other
    pigments. These are angular crystals of different hues, which at
    certain times of the year become more conspicuous than at others, a
    phenomenon which explains the variation in the colors of the leaves
    during the different seasons.

    It is evident that a tree is greatly dependent upon its leaves for
    the manufacture of food and one can, therefore, readily see why it
    is important to prevent destruction of the leaves by insects or
    through over-trimming.

  The root: The root develops in much the same manner as the crown. Its
    depth and spread will vary with the species but will also depend
    somewhat upon the condition of the soil around it. A deep or a dry
    soil will tend to develop a deep root, while a shallow or moist soil
    will produce a shallow root, Fig. 88.

    The numerous fine hairs which cover the roots serve the purpose of
    taking up food and water from the soil, while the heavy roots help
    to support the tree. The root-hairs are extremely tender, are easily
    dried out when exposed to the sun and wind, and are apt to become
    overheated when permitted to remain tightly packed for any length of
    time. These considerations are of practical importance in the
    planting of trees and in the application of fertilizers. It is these
    fine rootlets far away from the trunk of the tree that have to be
    fed, and all fertilizers must, therefore, be applied at points some
    distance from the trunk and not close to it, where merely the large,
    supporting roots are located. In the cultivation of trees the same
    principle holds true.

Requirements of trees: Trees are dependent upon certain soil and
    atmospheric conditions which influence their growth and development.

  (1) Influence of moisture: The form of the tree and its growth and
    structure depend greatly upon the supply of moisture. Botanists
    have taken the moisture factor as the basis of classification and
    have subdivided trees into those that grow in moist places
    (_hydrophytes_), those that grow in medium soils (_mesophytes_), and
    those that grow in dry places (_xerophytes_). Water is taken up by
    the roots of the tree from the soil. The liquid absorbed by the
    roots carries in solution the mineral salts--the food of the
    tree--and no food can be taken up unless it is in solution. Much of
    the water is used by the tree and an enormous amount is given off in
    the process of evaporation.

[Illustration: FIG. 89.--Dead Branches at the Top Caused by Insufficient
Water.]

    These facts will explain some of the fundamental principles in the
    care of trees. To a tree growing on a city street or on a lawn where
    nature fails to supply the requisite amount of water, the latter
    must be supplied artificially, especially during the hot summer
    months, or else dead branches may result as seen in Fig. 89. Too
    much thinning out of the crown causes excessive evaporation, and too
    much cutting out in woodlands causes the soil to dry and the trees
    to suffer for the want of moisture. This also explains why it is
    essential, in wooded areas, to retain on the ground the fallen
    leaves. In decomposing and mixing with the soil, the fallen leaves
    not only supply the trees with food material, but also tend to
    conserve moisture in the ground and to prevent the drying out of the
    soil. Raking off the leaves from wooded areas, a practice common in
    parks and on private estates--hurts the trees seriously. Some soils
    may have plenty of moisture, but may also be so heavily saturated
    with acids or salts that the tree cannot utilize the moisture, and
    it suffers from drought just the same as if there had been no
    moisture at all in the soil. Such soils are said to be
    "physiologically dry" and need treatment.

    In the development of disease, moisture is a contributing factor
    and, therefore, in cavities or underneath bandages where there is
    likely to be an accumulation of moisture, decay will do more damage
    than in places that are dry and exposed to the sun.

  (2) Influence of soil: Soil is made up of fine particles of sand and
    rock and of vegetable matter called _humus_. A tree will require a
    certain soil, and unsuitable soils can be very often modified to
    suit the needs of the tree. A deep, moderately loose, sandy loam,
    however, which is sufficiently aerated and well supplied with
    water, will support almost any tree. Too much of any one constituent
    will make a soil unfit for the production of trees. If too much clay
    is present the soil becomes "stiff." If too much vegetable matter is
    present, the soil becomes "sour." The physical character of the soil
    is also important. By physical character is meant the porosity which
    results from breaking up the soil. This is accomplished by ploughing
    or cultivation. In nature, worms help to do this for the soil, but
    on streets an occasional digging up of the soil about the base of
    the tree is essential.

    Humus or the organic matter in the soil is composed of litter,
    leaves and animal ingredients that have decayed under the influence
    of bacteria. The more vegetable matter in the humus, the darker the
    soil; and therefore a good soil such as one finds on the upper
    surface of a well-tilled farm has quite a dark color. When, however,
    a soil contains an unusual quantity of humus, it is known as "muck,"
    and when there is still more humus present we find _peat_. Neither
    of these two soils is suitable for proper tree growth.

[Illustration: FIG. 90.--A Tree in the Open. Note the full development
of the wide crown with branches starting near the ground. The tree is
the European larch.]

  (3) Influence of light: Light is required by the leaves in the process
    of assimilation. Cutting off some of the light from a tree affects
    its form. This is why trees grown in the open have wide-spreading
    crowns with branches starting near the ground as in Fig. 90, while
    the same species growing in the forest produces tall, lanky trees,
    free from branches to but a few feet from the top as in Fig. 91.
    Some trees can endure more shade than others, but all will grow in
    full light. This explains why trees like the beech, hemlock, sugar
    maple, spruce, holly and dogwood can grow in the shade, while the
    poplar, birch and willow require light. It also explains why, in
    the forest, the lower branches die and fall off--a process known in
    Forestry as "natural pruning," The influence of light on the form of
    trees should be well understood by all those who plant trees and by
    those designing landscape effects.

[Illustration: FIG. 91.--A Tree in The Forest. Note the tall stem free
from branches and the small, narrow crown.]

  (4) Influence of heat: Trees require a certain amount of heat. They
    receive it partly from the sun and partly from the soil. Evaporation
    prevents the overheating of the crown. The main stem of the tree is
    heated by water from the soil; therefore trees in the open begin
    growth in the spring earlier than trees in the forest because the
    soil in the open is warmer. Shrubs begin their growth earlier than
    trees because of the nearness of their crowns to their root systems.
    This also explains why a warm rain will start vegetation quickly.
    Too much heat will naturally cause excessive drying of the roots or
    excessive evaporation from the leaves and therefore more water is
    needed by the tree in summer than in winter.

  (5) Influence of season and frost: The life processes of a tree are
    checked when the temperature sinks below a certain point. The tree
    is thus, during the winter, in a period of rest and only a few
    chemical changes take place which lead up to the starting of
    vegetation. In eastern United States, growth starts in April and
    ceases during the latter part of August or in early September. The
    different parts of a tree may freeze solid during the winter without
    injury, provided the tree is a native one. Exotic trees may suffer
    greatly from extreme cold. This is one of the main reasons why it is
    always advisable to plant native trees rather than those that are
    imported and have not yet been acclimatized. Frosts during
    mid-winter are not quite as injurious as early and late frosts and,
    therefore, if one is going to protect plants from the winter's cold,
    it is well to apply the covering early enough and to keep it on
    late enough to overcome this difficulty.

    The mechanical injuries from frost are also important. Snow and
    sleet will weigh down branches but rarely break them, while frost
    will cause them to become brittle and to break easily. Those who
    climb and prune trees should be especially cautious on frosty days.

  (6) Influence of air: On the under side of leaves and on other
    surfaces of a tree little pores known as _stomata_ may be found. In
    the bark of birch and cherry trees these openings are very
    conspicuous and are there known as _lenticels_. These pores are
    necessary for the breathing of the tree (respiration), whereby
    carbonic acid gas is taken in from the air and oxygen given out. The
    process of assimilation depends upon this breathing process and it
    is therefore evident that when the stomata are clogged as may occur
    where a tree is subjected to smoke or dust, the life processes of
    the tree will be interfered with. The same injurious effect results
    when the stomata of the roots are interfered with. Such interference
    may occur in cases where a heavy layer of soil is piled around the
    base of a tree, where the soil about the base of a tree is allowed
    to become compact, where a tree is planted too deep, or where the
    roots are submerged under water for any length of time. In any case
    the air cannot get to the roots and the tree suffers. Nature takes
    special cognizance of this important requirement in the case of
    cypress trees, which habitually grow under water. Here the trees are
    provided with special woody protuberances known as "cypress knees,"
    which emerge above water and take the necessary air. See Fig. 18.

Conclusions: From the foregoing it will be seen that trees have certain
    needs that nature or man must supply. These requirements differ
    with the different species, and in all work of planting and care as
    well as in the natural distribution of trees it is both interesting
    and necessary to observe these individual wants, to select species
    in accordance with local conditions and to care for trees in
    conformity with their natural needs.




CHAPTER V

WHAT TREES TO PLANT AND HOW


The following classification will show the value of the more important
trees for different kinds of planting. The species are arranged in the
order of their merit for the particular object under consideration and
the comments accompanying each tree are intended to bring out its
special qualifications for that purpose.

Conditions for tree growth in one part of the country differ from those
of another and these lists, especially applicable to the Eastern States,
may not at all fit some other locality.



TREES BEST FOR THE LAWN


DECIDUOUS

1.  American elm (_Ulmus americana_)

    One of the noblest of trees. Possesses a majestic, wide-spreading,
    umbrella-shaped crown; is easily transplanted, and is suited to a
    variety of soils.

2.  Pin oak (_Quercus palustris_)

    Has a symmetrical crown with low-drooping branches; requires a moist
    situation.

3.  European linden (_Tilia microphylla_)

    Possesses a beautiful shade-bearing crown; grows well in ordinary
    soil.

4.  Red maple (_Acer rubrum_)

    Shows pleasing colors at all seasons; grows best in a fairly rich,
    moist soil.

5.  Copper beech (_Fagus sylvatica_, _alropurpurea_)

    Exceedingly beautiful in form, bark, and foliage and possesses great
    longevity and sturdiness. It is difficult to transplant and
    therefore only small trees from 6 to 10 feet in height should be
    used.

6.  Coffee tree (_Gymnocladus dioicus_)

    A unique and interesting effect is produced by its coarse branches
    and leaves. It is free from insects and disease; requires plenty of
    light; will grow in poor soils.

7.  European white birch (_Belula alba_)

    A graceful tree and very effective as a single specimen on the lawn,
    or in a group among evergreens; should be planted in early spring,
    and special care taken to protect its tender rootlets.

8.  Gingko or Maiden-hair tree (_Gingko biloba_)

    Where there is plenty of room for the spread of its odd branches,
    the gingko makes a picturesque specimen tree. It is hardy and free
    from insect pests and disease.

9.  Horsechestnut (_Aesculus hippocastanum_)

    Carries beautiful, showy flowers, and has a compact, symmetrical
    low-branched crown; is frequently subject to insects and disease.
    The red flowering horsechestnut (_A. rubicunda_) is equally
    attractive.

[Illustration: FIG. 92.--A Lawn Tree. European Weeping Beech.]

10. Sugar maple (_Acer saccharum_)

    Has a symmetrical crown and colors beautifully in the fall; requires
    a rich soil and considerable moisture.

11. Soulange's magnolia (_Magnolia soulangeana_)

    Extremely hard and flowers in early spring before the leaves appear.

12. Flowering dogwood (_Cornus florida_)

    Popular for its beautiful white flowers in the early spring and the
    rich coloring of its leaves in the fall; does not grow to large
    size. The red-flowering variety of this tree, though sometimes not
    quite as hardy, is extremely beautiful.

13. Japanese maple (_Acer polymorphum_)

    It has several varieties of different hues and it colors beautifully
    in the fall; it does not grow to large size.


CONIFEROUS

14. Oriental spruce (_Picea orientalis_)

    Forms a dignified, large tree with a compact crown and low branches;
    is hardy.

15. Austrian pine (_Pinus austriaca_)

    Is very hardy; possesses a compact crown; will grow in soils of
    medium quality.

16. Bhotan pine (_Pinus excelsa_)

    Grows luxuriantly; is dignified and beautiful; requires a good soil,
    and in youth needs some protection from extreme cold.

17. White pine (_Pinus strobus_)

    Branches gracefully and forms a large, dignified tree; will thrive
    on a variety of soils.

18. European larch (_Larix europaea_)

    Has a beautiful appearance; thrives best in moist situations.

19. Blue spruce (_Picea pungens_)

    Extremely hardy; forms a perfect specimen plant for the lawn.

20. Japanese umbrella pine (_Sciadopitys verlicillata_)

    Very hardy; retains a compact crown. An excellent specimen plant
    when grouped with other evergreens on the lawn. Does not grow to
    large size.

21. Mugho pine (_Pinus mughus_)

    A low-growing evergreen; hardy; important in group planting.

22. Obtuse leaf Japanese cypress (_Retinospora obtusa_)

    Beautiful evergreen of small size; hardy; desirable for group
    planting.

23. English yew (_Taxus baccata_)

    An excellent evergreen usually of low form; suitable for the lawn,
    massed with others or as a specimen plant; will grow in the shade of
    other trees. There are various forms of this species of distinctive
    value.



TREES BEST FOR THE STREET

1.  Oriental sycamore (_Platanus orientalis_)

    Very hardy; will adapt itself to city conditions; grows fairly fast
    and is highly resistant to insects and disease.

2.  Norway maple (_Acer platanoides_)

    Very hardy; possesses a straight trunk and symmetrical crown; is
    comparatively free from insects and disease and will withstand the
    average city conditions.

3.  Red oak (_Quercus rubra_)

    Fastest growing of the oaks; very durable and highly resistant to
    insects and disease; will grow in the average soil of the city
    street.

[Illustration: FIG. 93.--Street Trees. Norway Maples.]

4.  Gingko (_Gingko biloba_)

    Hardy and absolutely free from insects and disease; suited for
    narrow streets, and will permit of close planting.

5.  European linden (_Tilia microphylla_)

    Beautiful shade-bearing crown; is very responsive to good soil and
    plenty of moisture.

6.  American elm (_Ulmus americana_)

    When planted in rows along an avenue, it forms a tall majestic
    archway of great beauty. It is best suited for wide streets and
    should be planted further apart than the other trees listed above.
    Requires a fairly good soil and plenty of moisture, and is therefore
    not suited for planting in the heart of a large city.

7.  Pin oak (_Quercus palustris_)

    This tree exhibits its greatest beauty when its branches are allowed
    to droop fairly low. It, moreover, needs plenty of moisture to
    thrive and the tree is therefore best suited for streets in suburban
    sections, where these conditions can be more readily met.

8.  Red maple (_Acer rubrum_)

    Beautiful in all seasons of the year; requires a rich soil and
    considerable moisture.



TREES BEST FOR WOODLAND


FOR OPEN PLACES

1.  Red oak (_Quercus rubra_)

    Grows rapidly to large size and produces valuable wood; will grow in
    poor soil.

2.  White pine (_Pinus strobus_)

    Rapid grower; endures but little shade; wood valuable; will do well
    on large range of soils.

3.  Red pine (_Pinus resinosa_)

    Very hardy; fairly rapid growing tree.

4.  Tulip tree (_Liriodendron tulipifera_)

    Grows rapidly into a stately forest tree with a clear tall trunk;
    wood valuable; requires a fairly moist soil. Use a small tree, plant
    in the spring, and pay special attention to the protection of the
    roots in planting.

5.  Black locust (_Robinia pseudacacia_)

    Grows rapidly; adapts itself to poor, sandy soils. The wood is
    suitable for posts and ties.

6.  White ash (_Fraxinus americana_)

    Grows rapidly; prefers moist situations. Wood valuable.

7. American elm (_Ulmus americana_)

    Grows rapidly to great height; will not endure too much shade; does
    best in a deep fertile soil. Wood valuable.

8. European larch (_Larix europaea_)

    Grows rapidly; prefers moist situations.

[Illustration: FIG. 94.--Woodland Trees. Red Oaks.]


FOR PLANTING UNDER THE SHADE OF OTHER TREES

9. Beech (_Fagus_)

    Will stand heavy shade; holds the soil well along banks and steep
    slopes. Both the American and the English species are desirable.

10. Hemlock (_Tsuga canadensis_)

    Will stand heavy shade and look effective in winter as well as in
    summer.

11. Dogwood (_Cornus florida_)

    Will grow under other trees; flowers beautifully in the spring and
    colors richly in the fall.

12. Blue beech (_Carpinus caroliniana_)

    Native to the woodlands of the Eastern States; looks well in spring
    and fall.



TREES BEST FOR SCREENING

1. Hemlock (_Tsuga canadensis_)

    Will stand shearing and will screen in winter as well as in summer.
    Plant from 2 to 4 feet apart to form a hedge.

2. Osage orange (_Toxylon pomiferum_)

    Very hardy. Plant close.

3. English hawthorn (_Crataegus oxyacantha_)

    Flowers beautifully and grows in compact masses. Plant close.

4. Lombardy poplar (_Populus nigra var. italica_)

    Forms a tall screen and grows under the most unfavorable conditions.
    Plant 8 to 12 feet apart.



Quality of trees: Trees grown in a nursery are preferable for
    transplanting to trees grown in the forest. Nursery-grown trees
    possess a well-developed root system with numerous fibrous rootlets,
    a straight stem, a symmetrical crown, and a well-defined leader.
    Trees grown in neighboring nurseries are preferable to those grown
    at great distances, because they will be better adapted to local
    climatic and soil conditions. The short distances over which they
    must be transported also will entail less danger to the roots
    through drying. For lawn planting, the branches should reach low to
    the ground, while for street purposes the branches should start at
    about seven feet from the ground. For street planting, it is also
    important that the stem should be perfectly straight and about two
    inches in diameter. For woodland planting, the form of the tree is
    of minor consideration, though it is well to have the leader well
    defined here as well as in the other cases. See Fig. 95.

When and how to procure the trees: The trees should be selected in the
    nursery personally. Some persons prefer to seal the more valuable
    specimens with leaden seals. Fall is the best time to make the
    selection, because at that time one can have a wider choice of
    material. Selecting thus early will also prevent delay in delivery
    at the time when it is desired to plant.

When to plant: The best time to plant trees is early spring, just before
    growth begins, and after the frost is out of the ground. From the
    latter part of March to the early part of May is generally the
    planting period in the Eastern States.

    Where one has to plant both coniferous and deciduous trees, it is
    best to get the deciduous in first, and then the conifers.

How to plant: The location of the trees with relation to each other
    should be carefully considered. On the lawn, they should be
    separated far enough to allow for the full spread of the tree. On
    streets, trees should be planted thirty to thirty-five feet apart
    and in case of the elm, forty to fifty feet. In woodlands, it is
    well to plant as close as six feet apart where small seedlings are
    used and about twelve feet apart in the case of trees an inch or
    more in diameter. An abundance of good soil (one to two cubic yards)
    is essential with each tree where the specimens used are an inch or
    two in diameter. A rich mellow loam, such as one finds on the
    surface of a well-tilled farm, is the ideal soil. Manure should
    never be placed in direct contact with the roots or stem of the
    tree.

    Protection of the roots from drying is the chief precaution to be
    observed during the planting process, and for this reason a cloudy
    day is preferable to a sunny day for planting. In case of
    evergreens, the least exposure of the roots is liable to result
    disastrously, even more so than in case of deciduous trees. This is
    why evergreens are lifted from the nursery with a ball of soil
    around the roots. All bruised roots should be cut off before the
    tree is planted, and the crown of the tree of the deciduous species
    should be slightly trimmed in order to equalize the loss of roots by
    a corresponding decrease in leaf surface.

    The tree should be set into the tree hole at the same depth that it
    stood in the nursery. Its roots, where there is no ball of soil
    around them, should be carefully spread out and good soil should be
    worked in carefully with the fingers among the fine rootlets. Every
    root fibre is thus brought into close contact with the soil. More
    good soil should be added (in layers) and firmly packed about the
    roots. The last layer should remain loose so that it may act as a
    mulch or as an absorbent of moisture. The tree should then be
    thoroughly watered.

[Illustration: FIG. 95.--Specifications for a Street Tree.]

After care: During the first season the tree should be watered and the
    soil around its base slightly loosened at least once a week,
    especially on hot summer days. Where trees are planted on streets,
    near the curb, they should also be fastened to stakes and protected
    with a wire guard six feet high. See Fig. 95. Wire netting of
    ½-inch mesh and 17 gauge is the most desirable material.

[Illustration: FIG. 96.--A Home Nursery. (Austrian pines in front.)]

Suggestions for a home or school nursery: Schools, farms, and private
    estates may conveniently start a tree nursery on the premises and
    raise their own trees. Two-year seedling trees or four-year
    transplants are best suited for this purpose. These may be obtained
    from several reliable nurseries in various parts of the country that
    make a specialty of raising small trees for such purposes. The cost
    of such trees should be from three to fifteen dollars per thousand.

    The little trees, which range from one to two feet in height, will
    be shipped in bundles. Immediately upon arrival, the bundles should
    be untied and the trees immersed in a pail containing water mixed
    with soil. The bundles should then be placed in the ground
    temporarily, until they can be set out in their proper places. In
    this process, the individual bundles should be slanted with their
    tops toward the south, and the spot chosen should be cool and shady.
    At no time should the roots of these plants be exposed, even for a
    moment, to sun and wind, and they should always be kept moist. The
    little trees may remain in this trench for two weeks without injury.
    They should then be planted out in rows, each row one foot apart for
    conifers and two feet for broadleaf trees. The individual trees
    should be set ten inches apart in the row. Careful weeding and
    watering is the necessary attention later on.




CHAPTER VI

THE CARE OF TREES



STUDY I. INSECTS INJURIOUS TO TREES AND HOW TO COMBAT THEM

In a general way, trees are attacked by three classes of insects, and
the remedy to be employed in each case depends upon the class to which
the insect belongs. The three classes of insects are:

1. Those that *chew* and swallow some portion of the leaf; as, for
example, the elm leaf beetle, and the tussock, gipsy, and brown-tail
moths.

2. Those that *suck* the plant juices from the leaf or bark; such as the
San José scale, oyster-shell, and scurfy scales, the cottony maple
scale, the maple phenacoccus on the sugar maples, and the various
aphides on beech, Norway maple, etc.

3. Those that *bore* inside of the wood or inner bark. The principal
members of this class are the leopard moth, the hickory-bark borer, the
sugar-maple borer, the elm borer, and the bronze-birch borer.

The chewing insects are destroyed by spraying the leaves with arsenate
of lead or Paris green. The insects feed upon the poisoned foliage and
thus are themselves poisoned.

The sucking insects are killed by a contact poison: that is, by spraying
or washing the affected parts of the tree with a solution which acts
externally on the bodies of the insects, smothering or stifling them.
The standard solutions for this purpose are kerosene emulsion, soap and
water, tobacco extract, or lime-sulfur wash.

[Illustration: FIG. 97.--A Gas-power Spraying Apparatus.]

The boring insects are eliminated by cutting out the insect with a
knife, by injecting carbon bisulphide into the burrow and clogging the
orifice immediately after injection with putty or soap, or in some cases
where the tree is hopelessly infested, by cutting down and burning the
entire tree.

[Illustration: FIG. 98.--A Barrel Hand-pump Spraying Outfit.]

For information regarding the one of these three classes to which any
particular insect belongs, and for specific instructions on the
application of a remedy, the reader is advised to write to his State
Entomologist or to the U.S. Bureau of Entomology at Washington, D.C. The
letter should state the name of the tree affected, together with the
character of the injury, and should be accompanied by a specimen of the
insect, or by a piece of the affected leaf or bark, preferably by both.
The advice received will be authentic and will be given without charge.

[Illustration: FIG. 99.--Egg-masses of the Tussock Moth.]

When to spray: _In the case of chewing insects_, the latter part of May
    is the time to spray. The caterpillars hatch from their eggs, and
    the elm leaf beetle leaves its winter quarters at that time. _In the
    case of sucking insects_, the instructions will have to be more
    specific, depending upon the particular insect in question. Some
    sucking insects can best be handled in May or early June when their
    young emerge, others can be effectively treated in the fall or
    winter when the trees are dormant.

How to spray: Thoroughness is the essential principle in all spraying.
    In the case of leaf-eating insects, this means covering every leaf
    with the poison and applying it to the under side of the leaves,
    where the insects generally feed. In the case of sucking insects,
    thoroughness means an effort to touch every insect with the spray.
    It should be borne in mind that the insect can be killed only when
    hit with the chemical. The solution should be well stirred, and
    should be applied by means of a nozzle that will coat every leaf
    with a fine, mist-like spray. Mere drenching or too prolonged an
    application will cause the solution to run off. Special precautions
    should be taken with contact poisons to see that the formula is
    correct. Too strong a solution will burn the foliage and tender
    bark.

Spraying apparatus: There are various forms of spraying apparatus in the
    market, including small knapsack pumps, barrel hand-pumps, and
    gasolene and gas-power sprayers, Figs. 97 and 98. Hose and nozzles
    are essential accessories. One-half inch, three-ply hose of the best
    quality is necessary to stand the heavy pressure and wear. Two
    50-foot lengths is the usual quantity required for use with a barrel
    hand-pump. Each line of hose should be supplied with a bamboo pole
    10 feet long, having a brass tube passed through it to carry the
    nozzle. The Vermorel nozzle is the best type to use. The cost of a
    barrel outfit, including two lines of hose, nozzles and truck,
    should be from $30 to $40. Power sprayers cost from $150 to $300 or
    more.

Spraying material:
  _Arsenate of lead_ should be used in the proportion Of 4 pounds of the
    chemical to 50 gallons of water. A brand of arsenate of lead
    containing at least 14 per cent of arsenic oxide with not more than
    50 per cent of water should be insisted upon. This spray may be used
    successfully against caterpillars and other leaf-eating insects in
    the spring or summer.

  _Whale-oil soap_ should be used at the rate of 1½ pounds of the soap
    to 1 gallon of hot water, if applied to the tree in winter. As a
    spray in summer, use 1 pound of the soap to 5 gallons of water. This
    treatment is useful for most sucking insects.

  _Lime-sulfur wash_ is an excellent material to use against sucking
    insects, such as the San José scale and other armored scales. The
    application of a lime-sulfur wash when put on during the dormant
    season is not likely to harm a tree and has such an excellent
    cleansing effect that the benefits to be derived in this direction
    alone are often sufficient to meet the cost of the treatment.
    Lime-sulfur wash consists of a mixture, boiled one hour, of 40
    pounds of lime and 80 pounds of sulfur, in 50 gallons of water. It
    may be had in prepared form and should then be used at the rate of 1
    gallon to about 9 gallons of water in winter or early spring before
    the buds open. At other times of the year and for the softer-bodied
    insects a more diluted mixture, possibly 1 part to 30 or 40 parts of
    water, should be used, varying with each case separately.

  _Kerosene emulsion_ consists of one-half pound of hard soap, 1 gallon
    of boiling water, and 2 gallons of kerosene. It may be obtained in
    prepared form and is then to be used at the rate of one part of the
    solution to nine parts of water when applied in winter or to the
    bark only in summer. Use 2 gallons of the solution to a 40-gallon
    barrel of water when applying it to the leaves in the summer.
    Kerosene emulsion is useful as a treatment for scale insects.

  _Tobacco water_ should be prepared by steeping one-half pound of
    tobacco stems or leaves in a gallon of boiling water and later
    diluting the product with 5 to 10 gallons of water. It is
    particularly useful for plant lice in the summer.

The life history of an insect: In a general way, all insects have four
    stages of transformation before a new generation is produced. It is
    important to consider the nature of these four stages in order that
    the habits of any particular insect and the remedies applicable in
    combating it may be understood.

    All insects develop from _eggs_, Fig. 99. The eggs then hatch into
    caterpillars or grubs, which is the _larva_ stage, in which most
    insects do the greatest damage to trees. The caterpillars or grubs
    grow and develop rapidly, and hence their feeding is most ravenous.
    Following the larva stage comes the third or _pupa_ stage, which is
    the dormant stage of the insect. In this stage the insect curls
    itself up under the protection of a silken cocoon like the tussock
    moth, or of a curled leaf like the brown-tail moth, or it may be
    entirely unsheltered like the pupa of the elm leaf beetle. After the
    pupa stage comes the _adult insect_, which may be a moth or a
    beetle.

    A study of the four stages of any particular insect is known as a
    study of its _life history_. The important facts to know about the
    life history of an insect are the stage in which it does most of its
    feeding, and the period of the year in which this occurs. It is also
    important to know how the insect spends the winter in order to
    decide upon a winter treatment.


IMPORTANT INSECTS


THE ELM LEAF BEETLE

Life history: The elm leaf beetle, Fig. 100, is annually causing the
    defoliation of thousands of elm trees throughout the United States.
    Several successive defoliations are liable to kill a tree. The
    insects pass the winter in the beetle form, hiding themselves in
    attics and wherever else they can secure shelter. In the middle of
    May when the buds of the elm trees unfold, the beetles emerge from
    their winter quarters, mate, and commence eating the leaves, thus
    producing little holes through them. While this feeding is going on,
    the females deposit little, bright yellow eggs on the under side of
    the leaves, which soon hatch into small larvae or grubs. The grubs
    then eat away the soft portion of the leaf, causing it to look like
    lacework. The grubs become full grown in twenty days, crawl down to
    the base of the tree, and there transform into naked, orange-colored
    pupae. This occurs in the early part of August. After remaining in
    the pupa stage about a week, they change into beetles again, which
    either begin feeding or go to winter quarters.

Remedies: There are three ways of combating this insect: First, by
    _spraying the foliage_ with arsenate of lead in the latter part of
    May while the beetles are feeding, and repeating the spraying in
    June when the larvae emerge. The spraying method is the one most to
    be relied on in fighting this insect. A second, though less
    important remedy, consists in _destroying the pupae_ when they
    gather in large quantities at the base of the tree. This may be
    accomplished by gathering them bodily and destroying them, or by
    pouring hot water or a solution of kerosene over them. In large
    trees it may be necessary to climb to the crotches of the main limbs
    to get some of them. The third remedy lies in gathering and
    _destroying the adult beetles_ when found in their winter quarters.
    The application of bands of burlap or "tanglefoot," or of other
    substances often seen on the trunks of elm trees is useless, since
    these bands only prevent the larvae from crawling down from the
    leaves to the base and serve to prevent nothing from crawling up.
    Scraping the trunks of elm trees is also a waste of effort.

[Illustration: FIG. 100.--The Elm Leaf Beetle. (After Dr. E.P. Felt.)

1. Egg cluster, enlarged. 1a. Single egg, greatly enlarged. 2. Young
larva, enlarged. 3. Full grown larva, much enlarged. 4. Pupa, enlarged.
5. Overwintered beetle, enlarged. 6. Fresh, brightly colored beetle,
enlarged. 7. Under surface of leaf showing larvae feeding. 8. Leaf eaten
by larvae. 9. Leaf showing holes eaten by beetles.]


THE TUSSOCK MOTH

Life history: This insect appears in the form of a red-headed,
    yellow-colored caterpillar during the latter part of May, and in
    June and July. The caterpillars surround themselves with silken
    cocoons and change into pupae. The mature moths emerge from the
    cocoons after a period of about two weeks, and the females, which
    are wingless, soon deposit their eggs on the bark of trees, on
    twigs, fences, and other neighboring objects. These eggs form white
    clusters of nearly 350 individual eggs each, and are very
    conspicuous all winter, see Fig. 101.

Remedies: There are two ways of combating this insect: (1) By spraying
    with arsenate of lead for the caterpillars during the latter part of
    May and early June. (2) By removing and destroying the egg masses in
    the fall or winter.

[Illustration: FIG. 101.--The Tussock Moth. (After Dr. E.P. Felt.)

1. Caterpillar. 2. Male moth. 3. Female moth laying eggs. 4 Cocoons. 5.
Cast skins of caterpillar. 6. Work of young caterpillar. 7. Male pupa. 8
and 9. Girdled branches.]


THE GIPSY MOTH

Life history: This insect, imported from Europe to this country in 1868,
    has ever since proved a serious enemy of most shade, forest, and
    fruit trees in the New England States. It even feeds on
    evergreens, killing the trees by a single defoliation.

    The insect appears in the caterpillar stage from April to July. It
    feeds at night and rests by day. The mature caterpillar, which is
    dark in color, may be recognized by rows of blue and red spots along
    its back. After July, egg masses are deposited by the female moths
    on the bark of trees, and on leaves, fences, and other neighboring
    objects. Here they remain over the winter until they hatch in the
    spring. The flat egg masses are round or oval in shape, and are
    yellowish-brown in color. See Fig. 102.

Remedies: Spray for the caterpillars in June with arsenate of lead and
    apply creosote to the egg masses whenever found.


THE BROWN-TAIL MOTH

Life history: This insect was introduced here from Europe in 1890 and
    has since done serious damage to shade, forest, and fruit trees, and
    to shrubs in the New England States.

    It appears in the caterpillar stage in the early spring and
    continues to feed on the leaves and buds until the last of June.
    Then the caterpillars pupate, the moths come out, and in July and
    August the egg clusters appear. These hatch into caterpillars which
    form nests for themselves by drawing the leaves together. Here they
    remain protected until the spring. See Fig. 103.

Remedies: Collect the winter nests from October to April and burn them.
    Also spray the trees for caterpillars in early May and especially in
    August with arsenate of lead.

[Illustration: FIG. 102.--The Gipsy Moth. (After F.W. Rane Mass. State
Forester.)]

[Illustration: FIG. 103.--The Brown-tail Moth. (After F.W. Rane, Mass.
State Forester.)]

[Illustration: FIG. 104.--Larva of the Leopard Moth.]


THE FALL WEBWORM

The caterpillars of this insect congregate in colonies and surround
themselves with a web which often reaches the size of a foot or more in
diameter. These webs are common on trees in July and August. Cutting off
the webs or burning them on the twigs is the most practical remedy.

[Illustration: FIG. 105.--Branch Showing Work of the Leopard Moth Larva.]


THE LEOPARD MOTH

Life history: This insect does its serious damage in the grub form. The
    grubs which are whitish in color with brown heads, and which vary in
    size from 3/8 of an inch to 3 inches in length (Fig. 104), may be
    found boring in the wood of the branches and trunk of the tree all
    winter. Fig. 105. The leopard moth requires two years to complete
    its round of life. The mature moths are marked with dark spots
    resembling a leopard's skin, hence the name. Fig. 106. It is one of
    the commonest and most destructive insects in the East and is
    responsible for the recent death of thousands of the famous elm
    trees in New Haven and Boston. Fig. 107.

[Illustration: FIG. 106.--The Leopard Moth.]

Remedies: Trees likely to be infested with this insect should be
    examined three or four times a year for wilted twigs, dead branches,
    and strings of expelled frass; all of which may indicate the
    presence of this borer. Badly infested branches should be cut off
    and burned. Trees so badly infested that treatment becomes too
    complicated should be cut down and destroyed. Where the insects are
    few and can be readily reached, an injection of carbon bisulphide
    into the burrow, the orifice of which is then immediately closed
    with soap or putty, will often destroy the insects within.

[Illustration: FIG. 107.--Elm Tree Attacked by the Leopard Moth.]


THE HICKORY BARK BORER

Life history: This insect is a small brown or black beetle in its mature
    form and a small legless white grub in its winter stage. The beetles
    appear from June to August. In July they deposit their eggs in the
    outer sapwood, immediately under the bark of the trunk and larger
    branches. The eggs soon hatch and the grubs feed on the living
    tissue of the tree, forming numerous galleries. The grubs pass the
    winter in a nearly full-grown condition, transform to pupae in May,
    and emerge as beetles in June.

Remedies: The presence of the insect can be detected by the small holes
    in the bark of the trees and the fine sawdust which is ejected from
    these holes, when the insects are active. It is important to
    emphasize the advisability of detecting the fine sawdust because
    that is the best indication of the actual operations of the hickory
    bark borer. These holes, however, will not be noticeable until the
    insect has completed its transformation. In summer, the infested
    trees show wilted leaves and many dead twigs. Holes in the base of
    the petioles of these leaves are also signs of the working of the
    insect. Since the insect works underneath the bark, it is
    inaccessible for treatment and all infested trees should be cut down
    and burned, or the bark removed and the insects destroyed. This
    should be done before the beetles emerge from the tree in June.


PLANT LICE OR APHIDES

These often appear on the under side of the leaves of the beech, Norway
maple, tulip tree, etc. They excrete a sweet, sticky liquid called
"honey-dew," and cause the leaves to curl or drop. Spraying with
whale-oil soap solution formed by adding one pound of the soap to five
gallons of water is the remedy.



STUDY II. TREE DISEASES

Because trees have wants analogous to those of human beings, they also
have diseases similar to those which afflict human beings. In many cases
these diseases act like cancerous growths upon the human body; in some
instances the ailment may be a general failing due to improper feeding,
and in other cases it may be due to interference with the life processes
of the tree.

How to tell an ailing tree: Whatever the cause, an ailing tree will
    manifest its ailment by one or more symptoms.

    A change of color in the leaves at a time when they should be
    perfectly green indicates that the tree is not growing under normal
    conditions, possibly because of an insufficiency of moisture or
    light or an overdose of foreign gases or salts. Withering of the
    leaves is another sign of irregularity in water supply. Dead tops
    point to some difficulty in the soil conditions or to some disease
    of the roots or branches. Spotted leaves and mushroom-like growths
    or brackets protruding from the bark as in Fig. 108, are sure signs
    of disease.

    In attempting to find out whether a tree is healthy or not, one
    would therefore do well to consider whether the conditions under
    which it is growing are normal or not; whether the tree is suitable
    for the location; whether the soil is too dry or too wet; whether
    the roots are deprived of their necessary water and air by an
    impenetrable cover of concrete or soil; whether the soil is well
    drained and free from foreign gases and salts; whether the tree is
    receiving plenty of light or is too much exposed; and whether it is
    free from insects and fungi.

    If, after a thorough examination, it is found that the ailment has
    gone too far, it may not be wise to try to save the tree. A timely
    removal of a tree badly infested with insects or fungi may often be
    the best procedure and may save many neighboring trees from
    contagious infection. For this, however, no rules can be laid down
    and much will depend on the local conditions and the judgment and
    knowledge of the person concerned.

[Illustration: FIG. 108.--A Bracket Fungus (_Elfvingia megaloma_) on a
Tulip Tree.]

Fungi as factors of disease: The trees, the shrubs and the flowers with
    which we are familiar are rooted in the ground and derive their food
    both from the soil and from the air. There is, however, another
    group of plants,--_the fungi_,--the roots of which grow in trees and
    other plants and which obtain their food entirely from the trees or
    plants upon which they grow. The fungi cannot manufacture their own
    food as other plants do and consequently absorb the food of their
    host, eventually reducing it to dust. The fungi are thus
    disease-producing factors and the source of most of the diseases of
    trees.

    When we can see fungi growing on a tree we may safely assume that
    they are already in an advanced state of development. We generally
    discover their presence when their fruiting bodies appear on the
    surface of the tree as shown in Fig 109. These fruiting bodies are
    the familiar mushrooms, puffballs, toadstools or shelf-like brackets
    that one often sees on trees. In some cases they spread over the
    surface of the wood in thin patches. They vary in size from large
    bodies to mere pustules barely visible to the naked eye. Their
    variation in color is also significant, ranging from colorless to
    black and red but never green. They often emulate the color of the
    bark, Fig. 110.

    Radiating from these fruiting bodies into the tissues of the tree
    are a large number of minute fibers, comprising the _mycelium_ of
    the fungus. These fibers penetrate the body of the tree in all
    directions and absorb its food. The mycelium is the most important
    part of the fungous growth. If the fruiting body is removed, another
    soon takes its place, but if the entire mycelium is cut out, the
    fungus will never come back. The fruiting body of the fungus bears
    the seed or _spores_. These spores are carried by the wind or
    insects to other trees where they take root in some wound or crevice
    of the bark and start a new infestation.

[Illustration: FIG. 109.--The Fruiting Body of a Fungus.]

    The infestation will be favored in its growth if the spore can find
    plenty of food, water, warmth and darkness. As these conditions
    generally exist in wounds and cavities of trees, it is wise to keep
    all wounds well covered with coal tar and to so drain the cavities
    that moisture cannot lodge in them. This subject will be gone into
    more fully in the following two studies on "Pruning Trees" and "Tree
    Repair."

[Illustration: FIG. 110.--The Birch-fungus rot. (_Polyponis betulinus_
Fr.) Note the similarity in the color of the fruiting body and bark of
the tree.]

    While the majority of the fungi grow on the trunks and limbs of
    trees, some attack the leaves, some the twigs and others the roots.
    Some fungi grow on living wood some on dead wood and some on both.
    Those that attack the living trees are the most dangerous from the
    standpoint of disease.

The chestnut disease: The disease which is threatening the destruction
    of all the chestnut trees in America is a fungus which has, within
    recent years, assumed such vast proportions that it deserves special
    comment. The fungus is known as _Diaporthe parasitica_ (Murrill),
    and was first observed in the vicinity of New York in 1905. At that
    time only a few trees were known to have been killed by this
    disease, but now the disease has advanced over the whole chestnut
    area in the United States, reaching as far south as Virginia and as
    far west as Buffalo. Fig. 111 shows the result of the chestnut
    disease.

    The fungus attacks the cambium tissue underneath the bark. It enters
    through a wound in the bark and sends its fungous threads from the
    point of infection all around the trunk until the latter is girdled
    and killed. This may all happen within one season. It is not until
    the tree has practically been destroyed that the disease makes its
    appearance on the surface of the bark in the form of brown patches
    studded with little pustules that carry the spores. When once
    girdled, the tree is killed above the point of infection and
    everything above dies, while some of the twigs below may live until
    they are attacked individually by the disease or until the trunk
    below their origin is infected.

    All species of chestnut trees are subject to the disease. The
    Japanese and Spanish varieties appear to be highly resistant, but
    are not immune. Other species of trees besides chestnuts are not
    subject to the disease.

[Illustration: FIG. 111.--Chestnut Trees Killed by the Chestnut
Disease.]

    There is no remedy or preventive for this disease. From the nature
    of its attack, which is on the inner layer of the tree, it is
    evident that all applications of fungicides, which must necessarily
    be applied to the outside of the tree, will not reach the disease.
    Injections are impossible and other suggested remedies, such as
    boring holes in the wood for the purpose of inserting chemicals, are
    futile.

    The wood of the chestnut tree, within three or four years after its
    death, is still sound and may be used for telephone and telegraph
    poles, posts, railroad ties, lumber and firewood.

Spraying for fungous diseases: Where a fungous disease is attacking the
    leaves, fruit, or twigs, spraying with Bordeaux mixture may prove
    effective. The application of Bordeaux mixture is deterrent rather
    than remedial, and should therefore be made immediately before the
    disease appears. The nature of the disease and the time of treatment
    can be determined without cost, by submitting specimens of affected
    portions of the plant for analysis and advice to the State
    Agricultural Experiment Station or to the United States Department
    of Agriculture.

    Bordeaux mixture, the standard fungicide material, consists of a
    solution of 6 pounds of copper sulphate (blue vitriol) with 4 pounds
    of slaked lime in 50 gallons of water. It may be purchased in
    prepared form in the open market, and when properly made, has a
    brilliant sky-blue color. Spraying with Bordeaux mixture should be
    done in the fall, early spring, or early summer, but never during
    the period when the trees are in bloom.



STUDY III. PRUNING TREES


FUNDAMENTAL PRINCIPLES

Trees are very much like human beings in their requirements, mode of
life and diseases, and the general principles applicable to the care of
one are equally important to the intelligent treatment of the other. The
removal of limbs from trees, as well as from human beings, must be done
sparingly and judiciously. Wounds, in both trees and human beings, must
be disinfected and dressed to keep out all fungus or disease germs.
Fungous growths of trees are similar to human cancers, both in the
manner of their development and the surgical treatment which they
require. Improper pruning will invite fungi and insects to the tree,
hence the importance of a knowledge of fundamental principles in this
branch of tree care.

[Illustration: FIG. 112.--A Tree Pruned Improperly and too Severely.]

Time: Too much pruning at one time should never be practiced (Fig. 112),
    and no branch should be removed from a tree without good reason for
    so doing. Dead and broken branches should be removed as soon as
    observed, regardless of any special pruning season, because they are
    dangerous, unsightly and carry insects and disease into the heart of
    the tree. But all other pruning, whether it be for the purpose of
    perfecting the form in shade trees, or for increasing the production
    of fruit in orchard trees, should be confined to certain seasons.
    Shade and ornamental trees can best be pruned in the fall, while the
    leaves are still on the tree and while the tree itself is in
    practically a dormant state.

Proper cutting: All pruning should be commenced at the top of the tree
    and finished at the bottom. A shortened branch (excepting in poplars
    and willows, which should be cut in closely) should terminate in
    small twigs which may draw the sap to the freshly cut wound; where a
    branch is removed entirely, the cut should be made-close and even
    with the trunk, as in Fig. 113. Wherever there is a stub left after
    cutting off a branch, the growing tissue of the tree cannot cover it
    and the stub eventually decays, falls out and leaves a hole (see
    Fig. 114), which serves to carry disease and insects to the heart of
    the tree. This idea of close cutting cannot be over-emphasized.

    Where large branches have to be removed, the splitting and ripping
    of the bark along the trunk is prevented by making one cut beneath
    the branch, about a foot or two away from the trunk, and then
    another above, close to the trunk.

[Illustration: FIG. 113.--Branches Properly Cut Close to the Trunk.]

Too severe pruning: In pruning trees, many people have a tendency to cut
    them back so severely as to remove everything but the bare trunk and
    a few of the main branches. This process is known as "heading
    back." It is a method, however, which should not be resorted to
    except in trees that are very old and failing, and even there only
    with certain species, like the silver maple, sycamore, linden and
    elm. Trees like the sugar maple will not stand this treatment at
    all. The willow is a tree that will stand the process very readily
    and the Carolina poplar must be cut back every few years, in order
    to keep its crown from becoming too tall, scraggy and unsafe.

[Illustration: FIG. 114.--A Limb Improperly Cut. Note how the stub is
decaying and the resulting cavity is becoming diseased.]

Covering wounds: The importance of immediately covering all wounds with
    coal tar cannot be overstated. If the wound is not tarred, the
    exposed wood cracks, as in Fig. 115, providing suitable quarters for
    disease germs that will eventually destroy the body of the tree.
    Coal tar is by far preferable to paint and other substances for
    covering the wound. The tar penetrates the exposed wood, producing
    an antiseptic as well as a protective effect. Paint only forms a
    covering, which may peel off in course of time and which will later
    protrude from the cut, thus forming, between the paint and the wood,
    a suitable breeding place for the development of destructive fungi
    or disease. The application of tin covers, burlap, or other bandages
    to the wound is equally futile and in most cases even injurious.

[Illustration: FIG. 115.--Result of a Wound not Covered with Coal Tar.
The exposed wood cracked and decay set in.]


SPECIAL CONSIDERATIONS

Pruning shade trees: Here, the object is to produce a symmetrical crown
    and to have the lowest branches raised from the ground sufficiently
    high to enable pedestrians to pass under with raised umbrellas. Such
    pruning should, therefore, necessarily be light and confined to the
    low limbs and dead branches.

Pruning lawn trees: Here the charm of the tree lies in the low reach of
    the branches and the compactness of the crown. The pruning should,
    therefore, be limited to the removal of dead and diseased branches
    only.

Pruning forest trees: Forest trees have a greater commercial value when
    their straight trunks are free from branches. In the forest, nature
    generally accomplishes this result and artificial pruning seldom has
    to be resorted to. Trees in the forest grow so closely together that
    they shut out the sunlight from their lower limbs, thus causing the
    latter to die and fall off. This is known as natural pruning. In
    some European forests, nature is assisted in its pruning by workmen,
    who saw off the side branches before they fall of their own accord;
    but in this country such practice would be considered too expensive,
    hence it is seldom adopted.


TOOLS USED IN PRUNING

Good tools are essential for quick and effective work in pruning. Two or
three good saws, a pair of pole-shears, a pole-saw, a 16-foot single
ladder, a 40-foot extension ladder of light spruce or pine with hickory
rungs, a good pruning knife, plenty of coal tar, a fire-can to heat the
tar, a pole-brush, a small hand brush and plenty of good rope comprise
the principal equipment of the pruner.


SUGGESTIONS FOR THE SAFETY OF TREE CLIMBERS

1. Before climbing a tree, judge its general condition. The trunk of a
tree that shows age, disease, or wood-destroying insects generally has
its branches in an equally unhealthy condition.

2. The different kinds of wood naturally differ in their strength and
elasticity. The soft and brash woods need greater precautions than the
strong and pliable ones. The wood of all the poplars, the ailanthus, the
silver maple and the chestnut, catalpa and willow is either too soft or
too brittle to be depended upon without special care. The elm, hickory
and oak have strong, flexible woods and are, therefore, safer than
others. The red oak is weaker than the other oaks. The sycamore and
beech have a tough, cross-grained wood which is fairly strong. The
linden has a soft wood, while the ash and gum, though strong and
flexible, are apt to split.

3. Look out for a limb that shows fungous growths. Every fungus sends
fibers into the main body of the limb which draw out its sap. The
interior of the branch then loses its strength and becomes like a
powder. Outside appearances sometimes do not show the interior
condition, but one should regard a fungus as a danger sign.

4. When a limb is full of holes or knots, it generally indicates that
borers have been working all kinds of galleries through it, making it
unsafe. The silver maple and sycamore maple are especially subject to
borers which, in many cases, work on the under side of the branch so
that the man in the tree looking down cannot see its dangerous
condition.

5. A dead limb with the bark falling off indicates that it died at least
three months before and is, therefore, less safe than one with its bark
tightly adhering to it.

6. Branches are more apt to snap on a frosty day when they are covered
with an icy coating than on a warm summer day.

7. Always use the pole-saw and pole-shears on the tips of long branches,
and use the pole-hook in removing dead branches of the ailanthus and
other brittle trees where it would be too dangerous to reach them
otherwise.

8. Be sure of the strength of a branch before tying an extension ladder
to it.



STUDY IV. TREE REPAIR

Where trees have been properly cared for from their early start, wounds
and cavities and their subsequent elaborate treatment have no place. But
where trees have been neglected or improperly cared for, wounds and
cavities are bound to occur and early treatment becomes a necessity.

There are two kinds of wounds on trees: (1) surface wounds, which do not
extend beyond the inner bark, and (2) deep wounds or cavities, which may
range from a small hole in a crotch to the hollow of an entire trunk.

Surface wounds: Surface wounds (Fig. 116) are due to bruised bark, and a
    tree thus injured can no longer produce the proper amount of foliage
    or remain healthy very long. The reason for this becomes very
    apparent when one looks into the nature of the living or active
    tissue of a tree and notes how this tissue becomes affected by such
    injuries.

[Illustration: FIG. 116.--A Surface Wound Properly Freed from Decayed
Wood and Covered with Coal Tar.]

    This living or active tissue is known as the "cambium layer," and is
    a thin tissue situated immediately under the bark. It must
    completely envelop the stem, root and branches of the trees. The
    outer bark is a protective covering to this living layer, while the
    entire interior wood tissue chiefly serves as a skeleton or support
    for the tree. The cambium layer is the real, active part of the
    tree. It is the part which transmits the sap from the base of the
    tree to its crown; it is the part which causes the tree to grow by
    the formation of new cells, piled up in the form of rings around the
    heart of the tree; and it is also the part which prevents the
    entrance of insects and disease to the inner wood. From this it is
    quite evident that any injury to the bark, and consequently to this
    cambium layer alongside of it, will not only cut off a portion of
    the sap supply and hinder the growth of the tree to an extent
    proportional to the size of the wound, but will also expose the
    inner wood to the action of decay. The wound may, at first, appear
    insignificant, but, if neglected, it will soon commence to decay
    and thus to carry disease and insects into the tree. The tree then
    becomes hollow and dangerous and its life is doomed.

    Injury to the cambium layer, resulting in surface wounds, may be due
    to the improper cutting of a branch, to the bite of a horse, to the
    cut of a knife or the careless wielding of an axe, to the boring of
    an insect, or to the decay of a fungous disease. (See Fig. 117.)
    Whatever the cause, _the remedy lies in cleaning out all decayed
    wood, removing the loose bark and covering the exposed wood with
    coal tar_.

    In cutting off the loose bark, the edges should be made smooth
    before the coal tar is applied. Loose bark, put back against a tree,
    will never grow and will only tend to harbor insects and disease.
    Bandages, too, are hurtful because, underneath the bandage, disease
    will develop more rapidly than where the wound is exposed to the sun
    and wind. The application of tin or manure to wounds is often
    indulged in and is equally injurious to the tree. The secret of all
    wound treatment is to keep the wound _smooth, clean_ to the live
    tissue, _and well covered_ with coal tar.

    The chisel or gouge is the best tool to employ in this work. A sharp
    hawk-billed knife will be useful in cutting off the loose bark. Coal
    tar is the best material for covering wounds because it has both an
    antiseptic and a protective effect on the wood tissue. Paint, which
    is very often used as a substitute for coal tar, is not as
    effective, because the paint is apt to peel in time, thus allowing
    moisture and disease to enter the crevice between the paint and the
    wood.

[Illustration: FIG. 117.--A Neglected Surface Wound. Note the rough
surface of the wound, the want of a coal tar covering and the fungous
growth that followed.]

Cavities: Deep wounds and cavities are generally the result of stubs
    that have been permitted to rot and fall out. Surface wounds allowed
    to decay will deepen in course of time and produce cavities.
    Cavities in trees are especially susceptible to the attack of
    disease because, in a cavity, there is bound to exist an
    accumulation of moisture. With this, there is also considerable
    darkness and protection from wind and cold, and these are all ideal
    conditions for the development of disease.

    The successful application of a remedy, in all cavity treatment,
    hinges on this principal condition--_that all traces of disease
    shall be entirely eliminated before treatment is commenced_.

    Fungous diseases attacking a cavity produce a mass of fibers, known
    as the "mycelium," that penetrate the body of the tree or limb on
    which the cavity is located. In eliminating disease from a cavity,
    it is, therefore, essential to go _beyond_ the mere decaying surface
    and to cut out all fungous fibers that radiate into the interior of
    the tree. Where these fibers have penetrated so deeply that it
    becomes impossible to remove every one of them, the tree or limb
    thus affected had better be cut down. (Fig. 118.) The presence of
    the mycelium in wood tissue can readily be told by the discolored
    and disintegrated appearance of the wood.

    The filling in a cavity, moreover, should serve to prevent the
    accumulation of water and, where a cavity is perpendicular and so
    located that the water can be drained off without the filling, the
    latter should be avoided and the cavity should merely be cleaned out
    and tarred. (Fig. 116.) Where the disease can be entirely
    eliminated, where the cavity is not too large, and where a filling
    will serve the practical purpose of preventing the accumulation of
    moisture, the work of filling should be resorted to.

[Illustration: FIG. 118.--A Cavity Filled in a Tree that Should Have
Been Cut Down. Note how the entire interior is decayed and how the tree
fell apart soon after treatment.]

    Filling should be done in the following manner: First, the interior
    should be thoroughly freed from diseased wood and insects. The
    chisel, gouge, mall and knife are the tools, and it is better to
    cut deep and remove every trace of decayed wood than it is to leave
    a smaller hole in an unhealthy state. The inner surface of the
    cavity should then be covered with a coat of white lead paint, which
    acts as a disinfectant and helps to hold the filling. Corrosive
    sublimate or Bordeaux mixture may be used as a substitute for the
    white lead paint. A coat of coal tar over the paint is the next
    step. The cavity is then solidly packed with bricks, stones and
    mortar as in Fig. 119, and finished with a layer of cement at the
    mouth of the orifice. This surface layer of cement should not be
    brought out to the same plane with the outer bark of the tree, but
    should rather recede a little beyond the growing tissue (cambium
    layer) which is situated immediately below the bark, Fig. 120. In
    this way the growing tissue will be enabled to roll over the cement
    and to cover the whole cavity if it be a small one, or else to grow
    out sufficiently to overlap the filling and hold it as a frame holds
    a picture. The cement is used in mixture with sand in the proportion
    of one-third of cement to two-thirds of sand. When dry, the outer
    layer of cement should be covered with coal tar to prevent cracking.

[Illustration: FIG. 119.--A Cavity in the Process of being Filled.]

[Illustration: FIG. 120--The Same Cavity Properly Filled.]

Trees that tend to split: Certain species of trees, like the linden and
    elm, often tend to split, generally in the crotch of several limbs
    and sometimes in a fissure along the trunk of the tree. Midwinter is
    the period when this usually occurs and timely action will save the
    tree. The remedy lies in fastening together the various parts of the
    tree by means of bolts or chains.

    A very injurious method of accomplishing this end is frequently
    resorted to, where each of the branches is bound by an iron band and
    the bands are then joined by a bar. The branches eventually outgrow
    the diameter of the bands, causing the latter to cut through the
    bark of the limbs and to destroy them.

    Another method of bracing limbs together consists in running a
    single bolt through them and fastening each end of the bolt with a
    washer and nut. This method is preferable to the first because it
    allows for the growth of the limbs in thickness.

[Illustration: FIG. 121.--Diagram Showing the Triple-bar Method of
Fastening Limbs.]

    A still better method, however, consists in using a bar composed of
    three parts as shown in Fig. 121. Each of the two branches has a
    short bolt passed through it horizontally, and the two short bolts
    are then connected by a third bar. This arrangement will shift all
    the pressure caused by the swaying of the limbs to the middle
    connecting-bar. In case of a windstorm, the middle bar will be the
    one to bend, while the bolts which pass through the limbs will
    remain intact. The outer ends of the short bolts should have their
    washers and nuts slightly embedded in the wood of the tree, so that
    the living tissue of the tree may eventually grow over them in such
    a way as to hold the bars firmly in place and to exclude moisture
    and disease. The washers and nuts on the inner side of the limbs
    should also be embedded.

    A chain is sometimes advantageously substituted for the middle
    section of the bar and, in some cases, where more than two branches
    have to be joined together, a ring might take the place of the
    middle bar or chain.

    Bolts on a tree detract considerably from its natural beauty and
    should, therefore, be used only where they are absolutely necessary
    for the safety of the tree. They should be placed as high up in the
    tree as possible without weakening the limbs.




CHAPTER VII

FORESTRY



STUDY I. WHAT FORESTRY IS AND WHAT IT DOES

Although Forestry is not a new idea but, as a science and an art, has
been applied for nearly two thousand years, there are many persons who
still need an explanation of its aims and principles.

Forestry deals with the establishment, protection and utilization of
forests.

By establishment, is meant the planting of new forests and the cutting
of mature forests, in such a way as to encourage a natural growth of new
trees without artificial planting or seeding. The planting may consist
of sowing seed, or of setting out young trees. The establishment of a
forest by cutting may consist of the removal of all mature trees and
dependence upon the remaining stumps to reproduce the forest from
sprouts, or it may consist of the removal of only a portion of the
mature trees, thus giving the young seedlings on the ground room in
which to grow.

By protection, is meant the safeguarding of the forest from fire, wind,
insects, disease and injury for which man is directly responsible. Here,
the forester also prevents injury to the trees from the grazing and
browsing of sheep and goats, and keeps his forest so well stocked that
no wind can uproot the trees nor can the sun dry up the moist forest
soil.

[Illustration: FIG. 122.--A Forest of Bull Pine Cut on Forestry
Principles. (Photograph taken on the Black Hills National Forest, South
Dakota.)]

By utilization, is meant the conservative and intelligent harvesting of
the forest, with the aim of obtaining the greatest amount of product
from a given area, with the least waste, in the quickest time, and
without the slightest deterioration of the forest as a whole. The
forester cuts his mature trees, only, and generally leaves a sufficient
number on the ground to preserve the forest soil and to cast seed for
the production of a new crop. In this way, he secures an annual output
without hurting the forest itself. He studies the properties and values
of the different woods and places them where they will be most useful.
He lays down principles for so harvesting the timber and the
by-products of the forest that there will be the least waste and injury
to the trees which remain standing. He utilizes the forest, but does not
cut enough to interfere with the neighboring water-sheds, which the
forests protect.

[Illustration: 123.--A White Pine Plantation, in Rhode Island, Where the
Crowns of the Trees Have Met. The trees are fifteen years old and in
many cases every other tree had to be removed.]

Forestry, therefore, deals with a vast and varied mass of information,
comprising all the known facts relating to the life of a forest. It does
not deal with the individual tree and its planting and care,--that would
be arboriculture. Nor does it consider the grouping of trees for
aesthetic effect,--that would be landscape gardening. It concerns itself
with the forest as a community of trees and with the utilization of the
forest on an economic basis.

Each one of these activities in Forestry is a study in itself and
involves considerable detail, of which the reader may obtain a general
knowledge in the following pages. For a more complete discussion, the
reader is referred to any of the standard books on Forestry.

The life and nature of a forest: When we think of a forest we are apt to
    think of a large number of individual trees having no special
    relationship to each other. Closer observation, however, will reveal
    that the forest consists of a distinct group of trees, sufficiently
    dense to form an unbroken canopy of tops, and that, where trees grow
    so closely together, they become very interdependent. It is this
    interdependence that makes the forest different from a mere group of
    trees in a park or on a lawn. In this composite character, the
    forest enriches its own soil from year to year, changes the climate
    within its own bounds, controls the streams along its borders and
    supports a multitude of animals and plants peculiar to itself. This
    communal relationship in the life history of the forest furnishes a
    most interesting story of struggle and mutual aid. Different trees
    have different requirements with regard to water, food and light.
    Some need more water and food than others, some will not endure much
    shade, and others will grow in the deepest shade. In the open, a
    tree, if once established, can meet its needs quite readily and,
    though it has to ward off a number of enemies, insects, disease and
    windstorm--its struggle for existence is comparatively easy. In the
    forest, the conditions are different. Here, the tree-enemies have to
    be battled with, just as in the open, and in addition, instead of
    there being only a few trees on a plot of ground, there are
    thousands growing on the same area, all demanding the same things
    out of a limited supply. The struggle for existence, therefore,
    becomes keen, many falling behind and but few surviving.

[Illustration: FIG. 124.--Measuring the Diameter of a Tree and Counting
its Annual Rings.]

    This struggle begins with the seed. At first there are thousands of
    seeds cast upon a given area by the neighboring trees or by the
    birds and the winds. Of these, only a few germinate; animals feed on
    some of them, frost nips some and excessive moisture and unfavorable
    soil conditions prevent others from starting. The few successful
    ones soon sprout into a number of young trees that grow thriftily
    until their crowns begin to meet. When the trees have thus met, the
    struggle is at its height. The side branches encroach upon each
    other (Fig. 123), shut out the light without which the branches
    cannot live, and finally kill each other off. The upper branches vie
    with one another for light, grow unusually fast, and the trees
    increase in height with special rapidity. This is nature's method of
    producing clear, straight trunks which are so desirable for poles
    and large timber. In this struggle for dominance, some survive and
    tower above the others, but many become stunted and fail to grow,
    while the majority become entirely overtopped and succumb in the
    struggle; see Fig. 139.

    But in this strife there is also mutual aid. Each tree helps to
    protect its neighbors against the danger of being uprooted by the
    wind, and against the sun, which is liable to dry up the rich soil
    around the roots. This soil is different from the soil on the open
    lawn. It consists of an accumulation of decayed leaves mixed with
    inorganic matter, forming, together, a rich composition known as
    _humus_. The trees also aid each other in forming a close canopy
    that prevents the rapid evaporation of water from the ground.

    The intensity of these conditions will vary a great deal with the
    composition of the forest and the nature and habits of the
    individual trees. By composition, or type of forest, is meant the
    proportion in which the various species of trees are grouped; i.e.,
    whether a certain section of woodland is composed of one species or
    of a mixture of species. By habit is meant the requirements of the
    trees for light, water and food.

[Illustration: FIG. 125.--Mountain Slopes in North Carolina Well Covered
with Forests.]

    Some trees will grow in deep shade while others will demand the
    open. In the matter of water and food, the individual requirements
    of different trees are equally marked.

    The natural rapidity of growth of different species is also
    important, and one caring for a forest must know this rate of
    growth, not only as to the individual species, but also with respect
    to the forest as a whole. If he knows how fast the trees in a
    forest grow, both in height and diameter, he will know how much
    wood, in cubic feet, the forest produces in a year, and he can then
    determine how much he may cut without decreasing the capital stock.
    The rate of growth is determined in this way: A tree is cut and the
    rings on the cross-section surface are counted and measured; see
    Fig. 124. Each ring represents one year's growth. The total number
    of rings will show the age of the tree. By a study of the rings of
    the various species of trees on a given plot, the rate of growth of
    each species in that location can be ascertained and, by knowing the
    approximate number of trees of each species on the forest area, the
    rate of growth of the whole forest for any given year can be
    determined.

[Illustration: FIG. 126.--Bottom Lands Buried in Waste from Deforested
Mountains. Wu-t'ai-shan, Shan-si Province, China.]

[Illustration: FIG. 127.--Eroded Slope in Western North Carolina.]

Forests prevent soil erosion and floods: Forests help to regulate the
    flow of streams and prevent floods. Most streams are bordered by
    vast tracts of forest growths. The rain that falls on these forest
    areas is absorbed and held by the forest soil, which is permeated
    with decayed leaves, decayed wood and root fibers. The forest floor
    is, moreover, covered with a heavy undergrowth and thus behaves like
    a sponge, absorbing the water that falls upon it and then permitting
    it to ooze out gradually to the valleys and rivers below. A forest
    soil will retain one-half of its own quantity of water; i.e., for
    every foot in depth of soil there can be six inches of water and,
    when thus saturated, the soil will act as a vast, underground
    reservoir from which the springs and streams are supplied (Fig.
    125). Cut the forest down and the land becomes such a desert as is
    shown in Fig. 126. The soil, leaves, branches and fallen trees dry
    to dust, are carried off by the wind and, with the fall of rain, the
    soil begins to wash away and gullies, such as are shown in Fig. 127,
    are formed. Streams generally have their origins in mountain slopes
    and there, too, the forests, impeding the sudden run off of the
    water which is not immediately absorbed, prevent soil erosion.

[Illustration: FIG. 128.--Flood in Pittsburgh, Pa.]

    Where the soil is allowed to wash off, frequent floods are
    inevitable. Rain which falls on bare slopes is not caught by the
    crowns of trees nor held by the forest floor. It does not sink into
    the ground as readily as in the forest. The result is that a great
    deal of water reaches the streams in a short time and thus hastens
    floods. At other periods the streams are low because the water which
    would have fed them for months has run off in a few days. The farms
    are the first to suffer from the drouths that follow and, during the
    period of floods, whole cities are often inundated. Fig. 128 shows
    such a scene. The history of Forestry is full of horrible incidents
    of the loss of life and property from floods which are directly
    traceable to the destruction of the local forests and, on the other
    hand, there are many cases on record where flood conditions have
    been entirely obviated by the planting of forests. France and
    Germany have suffered from inundations resulting from forest
    devastation and, more than a hundred years ago, both of these
    countries took steps to reforest their mountain slopes, and thereby
    to prevent many horrible disasters.

[Illustration: FIG. 129.--Planting a Forest with Seedling Trees on the
Nebraska National Forest. The man on the right is placing the tree in a
slit just made with the spade. The man on the left is shoveling the dry
sand from the surface before making the slit for the tree.]

[Illustration: FIG. 130.--Diagrammatic Illustration of a Selection
Forest.]

How forests are established: New forests may be started from seed or
    from shoots, or suckers. If from seed, the process may be carried on
    in one of three ways:

    First, by sowing the seed directly on the land.

    Second, by first raising young trees in nurseries and later setting
    them out in their permanent locations in the forest. This method is
    applicable where quick results are desired, where the area is not
    too large, or in treeless regions and large open gaps where there
    is little chance for new trees to spring up from seed furnished by
    the neighboring trees. It is a method extensively practiced abroad
    where some of the finest forests are the result. The U.S.
    government, as well as many of the States, maintain forest-tree
    nurseries where millions of little trees are grown from seed and
    planted out on the National and State forests. Fig. 129 shows men
    engaged in this work. The fundamental principles of starting and
    maintaining a nursery have already been referred to in the chapter
    on "What Trees to Plant and How."

    The third method of establishing a forest from seed is by cutting
    the trees in the existing forest so that the seed falling from the
    remaining trees will, with the addition of light and space, readily
    take root and fill in the gaps with a vigorous growth of trees,
    without artificial seeding or planting. This gives rise to several
    methods of cutting or harvesting forests for the purpose of
    encouraging natural reproduction. The cutting may extend to single
    trees over the whole area or over only a part of the whole area.
    Where the cutting is confined to single trees, the system is known
    as the "Selection System," because the trees are selected
    individually, with a view to retaining the best and most vigorous
    stock and removing the overcrowding specimens and those that are
    fully mature or infested with disease or insects.

    Fig. 130 is a diagrammatic illustration of the operation of this
    system. In another system the cutting is done in groups, or in
    strips, and the number of areas of the groups or strips is extended
    from time to time until the whole forest is cleared. This system is
    illustrated in Fig. 131. Still another method consists in
    encouraging trees which will thrive in the shade, such as the beech,
    spruce and hemlock, to grow under light-demanding trees like the
    pine. This system presents a "two-storied" forest and is known by
    that name. The under story often has to be established by planting.

[Illustration: FIG. 131.--Diagrammatic Illustration of the Group or
Strip System.]

    In the system of reproducing forests from shoots or suckers, all
    trees of a certain species on a given area are cut off and the old
    stumps and roots are depended upon to produce a new set of sprouts,
    the strongest of which will later develop into trees. The coniferous
    trees do not lend themselves at all to this system of treatment,
    and, among the broadleaf trees, the species vary in their ability to
    sprout. Some, like the chestnut and poplar, sprout profusely; others
    sprout very little.

How forests are protected: Forestry also tries to protect the forests
    from many destructive agencies. Wasteful lumbering and fire are the
    worst enemies of the forest. Fungi, insects, grazing, wind, snow and
    floods are the other enemies.

[Illustration: FIG. 132.--The Result of a Forest Fire. The trees,
lodgepole pine and Englemann spruce, are all dead and down. Photograph
taken in the Colorado National Forest, Colorado.]

    By wasteful lumbering is meant that the forest is cut with no regard
    for the future and with considerable waste in the utilization of the
    product. Conservative lumbering, which is the term used by foresters
    to designate the opposite of wasteful lumbering, will be described
    more fully later in this study.

    Protection from fire is no less important than protection from
    wasteful lumbering. Forest fires are very common in this country and
    cause incalculable destruction to life and property; see Fig. 132.
    From ten to twelve million acres of forest-land are burnt over
    annually and the timber destroyed is estimated at fifty millions of
    dollars. The history of Forestry abounds in tales of destructive
    fires, where thousands of persons have been killed or left
    destitute, whole towns wiped out, and millions of dollars in
    property destroyed. In most cases, these uncontrollable fires
    started from small conflagrations that could readily, with proper
    fire-patrol, have been put out.

    There are various ways of fighting fires, depending on the character
    of the fire,--whether it is a surface fire, burning along the
    surface layer of dry leaves and small ground vegetation, a ground
    fire, burning below the surface, through the layer of soil and
    vegetable matter that generally lines the forest floor, or a top
    fire, burning high up in the trees.

    When the fire runs along the surface only, the injury extends to the
    butts of the trees and to the young seedlings. Such fires can be put
    out by throwing dirt or sand over the fire, by beating it, and,
    sometimes, by merely raking the leaves away.

    Ground fires destroy the vegetable mold which the trees need for
    their sustenance. They progress slowly and kill or weaken the roots
    of the trees.

[Illustration: FIG. 133.--A Top Fire near Bear Canyon, Arizona.]

    Top fires, Fig. 133, are the most dangerous, destroying everything
    in their way. They generally develop from surface fires, though
    sometimes they are started by lightning. They are more common in
    coniferous forests, because the leaves of hardwoods do not burn so
    readily. Checking the progress of a top fire is a difficult matter.
    Some fires will travel as rapidly as five miles an hour, and the
    heat is terrific. The only salvation for the forest lies, in many
    cases, in a sudden downpour of rain, a change of wind, or some
    barrier which the fire cannot pass. A barrier of this kind is often
    made by starting another fire some distance ahead of the principal
    one, so that when the two fires meet, they will die out for want of
    fuel. In well-kept forests, strips or lanes, free from inflammable
    material, are often purposely made through the forest area to
    furnish protection against top fires. Carefully managed forests are
    also patrolled during the dry season so that fires may be detected
    and attacked in their first stages. Look-out stations, watch-towers,
    telephone-connections and signal stations are other means frequently
    resorted to for fire protection and control. Notices warning campers
    and trespassers against starting fires are commonly posted in such
    forests. (Fig. 143.)

[Illustration: FIG. 134.--Sheep Grazing on Holy Cross National Forest,
Colorado. The drove consists of 1600 sheep, of which only part are shown
in the photograph.]

    The grazing of sheep, goats and cattle in the forest is another
    important source of injury to which foresters must give attention.
    In the West this is quite a problem, for, when many thousands of
    these animals pass through a forest (Fig. 134), there is often very
    little young growth left and the future reproduction of the forest
    is severely retarded. Grazing on our National Forests is regulated
    by the Government.

    As a means of protection against insects and fungi, all trees
    infested are removed as soon as observed and in advance of all
    others, whenever a lumbering operation is undertaken.

[Illustration: FIG. 135.--A Typical Montana Sawmill.]

How forests are harvested: Forestry and forest preservation require that
    a forest should be cut and not merely held untouched. But it also
    demands that the cutting shall be done on scientific principles, and
    that only as much timber shall be removed in a given time as the
    forest can produce in a corresponding period. After the cutting, the
    forest must be left in a condition to produce another crop of
    timber within a reasonable time: see Fig. 122. These fundamental
    requirements represent the difference between conservative lumbering
    and ordinary lumbering. Besides insuring a future supply of timber,
    conservative lumbering, or lumbering on forestry principles, also
    tends to preserve the forest floor and the young trees growing on
    it, and to prevent injury to the remaining trees through fire,
    insects and disease. It provides for a working plan by which the
    kind, number and location of the trees to be cut are specified, the
    height of the stumps is stipulated and the utilization of the wood
    and by-products is regulated.

    Conservative lumbering provides that the trees shall be cut as near
    to the ground as possible and that they shall be felled with the
    least damage to the young trees growing near by. The branches of the
    trees, after they have been felled, must be cut and piled in heaps,
    as shown in Fig. 122, to prevent fire. When the trunks, sawed into
    logs, are dragged through the woods, care is taken not to break down
    the young trees or to injure the bark of standing trees. Waste in
    the process of manufacture is provided against, uses are found for
    the material ordinarily rejected, and the best methods of handling
    and drying lumber are employed. Fig. 135 shows a typical sawmill
    capable of providing lumber in large quantities.

    In the utilization of the by-products of the forest, such as
    turpentine and resin, Forestry has devised numerous methods for
    harvesting the crops with greater economy and with least waste and
    injury to the trees from which the by-products are obtained. Fig.
    136 illustrates an improved method by which crude turpentine is
    obtained.

[Illustration: FIG. 136.--Gathering Crude Turpentine by the Cup and
Gutter Method. This system, devised by foresters, saves the trees and
increases the output.]

Forestry here and abroad: Forestry is practiced in every civilized
    country except China and Turkey. In Germany, Forestry has attained,
    through a long series of years, a remarkable state of scientific
    thoroughness and has greatly increased the annual output of the
    forests of that country.

    In France, Switzerland, Austria, Hungary, Norway, Sweden, Russia
    and Denmark, Forestry is also practiced on scientific principles and
    the government in each of these countries holds large tracts of
    forests in reserve. In British India one finds a highly efficient
    Forest Service and in Japan Forestry is receiving considerable
    attention.

    In the United States, the forest areas are controlled by private
    interests, by the Government and by the States. On privately owned
    forests, Forestry is practiced only in isolated cases. The States
    are taking hold of the problem very actively and in many of them we
    now find special Forestry Commissions authorized to care for vast
    areas of forest land reserved for State control. These Commissions
    employ technically trained foresters who not only protect the State
    forests, but also plant new areas, encourage forest planting on
    private lands and disseminate forestry information among the
    citizens. New York State has such a Commission that cares for more
    than a million acres of forest land located in the northern part of
    the State. Many other States are equally progressive.

    The United States Government is the most active factor in the
    preservation of our forests. The Government to-day owns over two
    hundred million acres of forest land, set aside as National Forests.
    There are one hundred and fifty individual reserves, distributed as
    shown in Fig. 137 and cared for by the Forest Service, a bureau in
    the Department of Agriculture. Each of the forests is in charge of a
    supervisor. He has with him a professional forester and a body of
    men who patrol the tract against fire and the illegal cutting of
    timber. Some of the men are engaged in planting trees on the open
    areas and others in studying the important forest problems of the
    region. Fig. 138.

[Illustration: FIG. 137.--Map Showing Our National Forests.]

[Illustration: FIG. 138.--Government Foresters in Missouri Studying the
Growth and Habits of Trees. They are standing in water three feet deep.]

    Where cutting is to be done on a National Forest, the conditions are
    investigated by a technically trained forester and the cutting is
    regulated according to his findings. Special attention is given to
    discovering new uses for species of trees which have hitherto been
    considered valueless, and the demand upon certain rare species is
    lessened by introducing more common woods which are suitable for use
    in their place.

    Aside from the perpetuation of the national forests, the U.S.
    Forest Service also undertakes such tree studies as lie beyond the
    power or means of private individuals. It thus stands ready to
    cooperate with all who need assistance.



STUDY II. CARE OF THE WOODLAND

Almost every farm, large private estate or park has a wooded area for
the purpose of supplying fuel or for enhancing the landscape effect of
the place. In most instances these wooded areas are entirely neglected
or are so improperly cared for as to cause injury rather than good. In
but very few cases is provision made for a future growth of trees after
the present stock has gone. Proper attention will increase and
perpetuate a crop of good trees just as it will any other crop on the
farm, while the attractiveness of the place may be greatly enhanced
through the intelligent planting and care of trees.

How to judge the conditions: A close examination of the wooded area may
    reveal some or all of the following unfavorable conditions:

    The trees may be so crowded that none can grow well. A few may have
    grown to large size but the rest usually are decrepit, and
    overtopped by the larger trees. They are, therefore, unable, for the
    want of light and space, to develop into good trees. Fig. 139 shows
    woodland in such condition.

[Illustration: FIG. 139.--Woodland which Needs Attention. The trees are
overcrowded.]

    There may also be dead and dying trees, trees infested with
    injurious insects and fungi and having any number of decayed
    branches. The trees may be growing so far apart that their trunks
    will be covered with suckers as far down as the ground, or there may
    be large, open gaps with no trees at all. Here the sun, striking
    with full force, may be drying up the soil and preventing the
    decomposition of the leaves. Grass soon starts to grow in these open
    spaces and the whole character of the woodland changes as shown in
    Figs. 140 and 141.

[Illustration: FIG. 140.--First Stage of Deterioration. The woodland is
too open and grass has taken the place of the humus cover.]

    Where any of these conditions exist, the woodland requires
    immediate attention. Otherwise, as time goes on, it deteriorates
    more and more, the struggle for space among the crowded and
    suppressed trees becomes more keen, the insects in the dying trees
    multiply and disease spreads from tree to tree. Under such
    conditions, the soil deteriorates and the older trees begin to
    suffer.

[Illustration: FIG. 141.--Second Stage of Deterioration. The Surface
Soil of the Wooded Area Has Washed Away and the Trees Have Died.]

    The attention required for the proper care of woodland may be summed
    up under the four general heads of _soil preservation_, _planting_,
    _cutting_, and _protection_.

Improvement by soil preservation: The soil in a wooded area can best be
    preserved and kept rich by doing two things; by retaining the
    fallen leaves on the ground and by keeping the ground well covered
    with a heavy growth of trees, shrubs and herbaceous plants. The
    fallen leaves decompose, mix with the soil and form a dark-colored
    material known as _humus_. The humus supplies the tree with a
    considerable portion of its food and helps to absorb and retain the
    moisture in the soil upon which the tree is greatly dependent. A
    heavy growth of trees and shrubs has a similar effect by serving to
    retain the moisture in the soil.

Improvement by planting: The planting of new trees is a necessity on
    almost any wooded area. For even where the existing trees are in
    good condition, they cannot last forever, and provision must be made
    for others to take their place after they are gone. The majority of
    the wooded areas in our parks and on private estates are not
    provided with a sufficient undergrowth of desirable trees to take
    the place of the older ones. Thus, also, the open gaps must be
    planted to prevent the soil from deteriorating.

    Waste lands on farms which are unsuited for farm crops often offer
    areas on which trees may profitably be planted. These lands are
    sufficiently good in most cases to grow trees, thus affording a
    means of turning into value ground which would otherwise be
    worthless. It has been demonstrated that the returns from such
    plantations at the end of fifty years will yield a six per cent
    investment and an extra profit of $151.97 per acre, the expense
    totaling at the end of fifty years, $307.03. The value of the land
    is estimated at $4 per acre and the cost of the trees and planting
    at $7 per acre. The species figured on here is white pine, one of
    the best trees to plant from a commercial standpoint. With other
    trees, the returns will vary accordingly.

[Illustration: FIG. 142.--A Farm Woodlot.]

    The usual idea that it costs a great deal to plant several thousand
    young trees is erroneous. An ordinary woodlot may be stocked with a
    well-selected number of young trees at a cost less than the price
    generally paid for a dozen good specimen trees for the front lawn.
    It is not necessary to underplant the woodlot with big trees. The
    existing big trees are there to give character to the forest and the
    new planting should be done principally as a future investment and
    as a means of perpetuating the life of the woodlot. Young trees are
    even more desirable for such planting than the older and more
    expensive ones. The young trees will adapt themselves to the local
    soil and climatic conditions more easily than the older ones. Their
    demand for food and moisture is more easily satisfied, and because
    of their small cost, one can even afford to lose a large percentage
    of them after planting.

    The young plants should be two-year-old seedlings or three-year-old
    "transplants."

    Two-year-old seedlings are trees that have been grown from the seed
    in seed beds until they reach that age. They run from two to fifteen
    inches in height, depending upon the species.

    Three-year-old "transplants" have been grown from the seed in seed
    beds and at the end of the first or second year have been taken up
    and transplanted into rows, where they grow a year or two longer.
    They are usually a little taller than the two-year-old seedlings,
    are much stockier and have a better root system. For this reason,
    three-year-old transplants are a little more desirable as stock for
    planting. They will withstand drought better than seedlings.

    The best results from woodland planting are obtained with
    native-grown material. Such stock is stronger, hardier and better
    acclimated. Foreign-grown stock is usually a little cheaper, owing
    to the fact that it has been grown abroad, under cheap labor
    conditions.

    The trees may be purchased from reputable dealers, of whom there are
    many in this country. These dealers specialize in growing young
    trees and selling them at the low cost of three to ten dollars per
    thousand. In States in which a Forestry Commission has been
    inaugurated, there have also been established State nurseries where
    millions of little trees are grown for reforestation purposes. In
    order to encourage private tree planting, the Forestry Commissions
    are usually willing to sell some of these trees at cost price, under
    certain conditions, to private land owners. Inquiries should be
    made to the State Forestry Commission.

    Great care must be taken to select the species most suitable for the
    particular soil, climatic and light conditions of the woodlot. The
    trees which are native to the locality and are found growing
    thriftily on the woodlot, are the ones that have proven their
    adaptability to the local conditions and should therefore be the
    principal species used for underplanting. A list from which to
    select the main stock would, therefore, vary with the locality. In
    the Eastern States it would comprise the usual hardy trees like the
    red, pin and scarlet oaks, the beech, the red and sugar maples, the
    white ash, the tulip tree, sycamore, sweet gum and locust among the
    deciduous trees; the white, Austrian, red, pitch and Scotch pines,
    the hemlock and the yew among the conifers.

    With the main stock well selected, one may add a number of trees and
    shrubs that will give to the woodland scene a pleasing appearance at
    all seasons. The brilliant autumnal tints of the sassafras,
    pepperidge, blue beech, viburnum, juneberry and sumach are
    strikingly attractive. The flowering dogwood along the drives and
    paths will add a charm in June as well as in autumn and an
    occasional group of white birch will have the same effect if planted
    among groups of evergreens. Additional undergrowth of native
    woodland shrubs, such as New Jersey tea, red-berried elder and
    blueberry for the Eastern States, will augment the naturalness of
    the scene and help to conserve the moisture in the soil.

    Two or three years' growth will raise these plants above all grass
    and low vegetation, and a sprinkling of laurel, rhododendron, hardy
    ferns and a few intermingling colonies of native wild flowers such
    as bloodroot, false Solomon's seal and columbines for the East, as
    a ground cover will put the finishing touches to the forest scene.

    As to methods of planting the little trees, the following
    suggestions may prove of value. As soon as the plants are received,
    they should be taken from the box and dipped in a thick puddle of
    water and loam. The roots must be thoroughly covered with the mud.
    Then the bundles into which the little trees are tied should be
    loosened and the trees placed in a trench dug on a slant. The dirt
    should be placed over the roots and the exposed parts of the plants
    covered with brush or burlap to keep away the rays of the sun.

    When ready for planting, a few plants are dug up, set in a pail with
    thin mud at the bottom and carried to the place of planting. The
    most economical method of planting is for one man to make the holes
    with a mattock. These holes are made about a foot in diameter, by
    scraping off the sod with the mattock and then digging a little hole
    in the dirt underneath. A second man follows with a pail of plants
    and sets a single plant in this hole with his hands, see Fig. 129,
    making sure that the roots are straight and spread out on the bottom
    of the hole. The dirt should then be packed firmly around the plant
    and pressed down with the foot.

Improvement by cutting: The removal of certain trees in a grove is often
    necessary to improve the quality of the better trees, increase their
    growth, make the place accessible, and enhance its beauty. Cutting
    in a wooded area should be confined to suppressed trees, dead and
    dying trees and trees badly infested with insects and disease. In
    case of farm woodlands, mature trees of market value may be cut, but
    in parks and on private estates these have a greater value when left
    standing. The cutting should leave a clean stand of well-selected
    specimens which will thrive under the favorable influence of more
    light and growing space. Considerable care is required to prevent
    injury to the young trees when the older specimens are cut and
    hauled out of the woods. The marking of the trees to be removed can
    best be done in summer when the dead and live trees can be
    distinguished with ease and when the requisite growing space for
    each tree can be judged better from the density of the crowns. The
    cutting, however, can be done most advantageously in winter.

    Immediately after cutting all diseased and infested wood should be
    destroyed. The sound wood may be utilized for various purposes. The
    bigger logs may be sold to the local lumber dealers and the smaller
    material may be used for firewood. The remaining brush should be
    withdrawn from the woodlot to prevent fire during the dry summer
    months.

    In marking trees for removal, a number of considerations are to be
    borne in mind besides the elimination of dead, diseased and
    suppressed trees. When the marker is working among crowding trees of
    equal height, he should save those that are most likely to grow into
    fine specimen trees and cut out all those that interfere with them.
    The selection must also favor trees which are best adapted to the
    local soil and climatic conditions and those which will add to the
    beauty of the place. In this respect the method of marking will be
    different from that used in commercial forestry, where the aim is to
    net the greatest profit from the timber. In pure forestry practice,
    one sees no value in such species as dogwood, ironwood, juneberry,
    sumac and sassafras, and will therefore never allow those to grow up
    in abundance and crowd out other trees of a higher market value. But
    on private estates and in park woodlands where beauty is an
    important consideration, such species add wonderful color and
    attractiveness to the forest scene, especially along the roads and
    paths, and should be favored as much as the other hardier trees. One
    must not mark too severely in one spot or the soil will be dried out
    from exposure to sun and wind. When the gaps between the trees are
    too large, the trees will grow more slowly and the trunks will
    become covered with numerous shoots or suckers which deprive the
    crowns of their necessary food and cause them to "die back." Where
    the trees are tall and slim or on short and steep hillsides, it is
    also important to be conservative in marking in order that the stand
    may not be exposed to the dangers of windfall. No hard-and-fast rule
    can be laid down as to what would constitute a conservative
    percentage of trees to cut down. This depends entirely on the local
    conditions and on the exposure of the woodlot. But in general it is
    not well to remove more than twenty per cent of the stand nor to
    repeat the cutting on the same spot oftener than once in five or six
    years. The first cutting will, of course, be the heaviest and all
    subsequent cuttings will become lighter and lighter until the
    woodlot is put in good growing condition. On private estates and
    parks, where beauty is the chief aim, the woodland should be kept as
    natural, informal and as thick as possible. Where the woodland is
    cut up by many paths and drives, density of vegetation will add to
    the impression of depth and distance.

Protection: This subject has already been discussed considerably in the
    previous study on Forestry, and here it becomes necessary merely to
    add a few suggestions with special reference to private and park
    woodlands.

    Guarding woodlands from _fire_ is the most important form of
    protection. Surface fires are very common on small woodland holdings
    and the damage done to the standing vegetation is generally
    underestimated. An ordinary ground or surface fire on a woodland
    area will burn up the leaf-litter and vegetable mold, upon which the
    trees depend so much for food and moisture, and will destroy the
    young seedlings on the ground. Where the fire is a little more
    severe, the older trees are badly wounded and weakened and the
    younger trees are frequently killed outright. Insects and disease
    find these trees an easy prey, and all related forest conditions
    commence to deteriorate.

    Constant watchfulness and readiness to meet any emergency are the
    keynote of effective fire protection. Notices similar to the one
    shown in Fig. 143 often help to prevent fires. It is also helpful to
    institute strict rules against dropping lighted matches or tobacco,
    or burning brush when the ground is very dry, or leaving smouldering
    wood without waiting to see that the fire is completely out. There
    should be many roads and foot-paths winding through the woodland in
    order that they may serve as checks or "fire lanes" in time of fire.
    These roads and paths should be kept free from brush and leaves and
    should be frequently patrolled. When made not too wide,
    unpretentious and in conformity with the natural surroundings, such
    drives and paths can become a very interesting feature of the place,
    winding through the woodland, exposing its charms and affording
    opportunity for pleasant driving and walking. The borders of the
    paths can be given special attention by placing the more beautiful
    native shrubs in prominent positions where they can lend increased
    attractiveness.

    In case of fire, it should be possible to call for aid by telephone
    directly from the woodland and to find within easy reach the tools
    necessary to combat fire. It is also important to obtain the
    co-operation of one's neighbors in protecting the adjoining
    woodlands, because the dangers from insects, disease and fire
    threatening one bit of woodland area are more or less dependent upon
    the conditions in the adjoining woodland.

[Illustration: FIG. 143.--Poster Suitable for Private Woodlands and
Forest Parks. The translations in Italian and Polish have been used by
the writer in this particular instance to meet the local needs.]

    As to other forms of protection, passing mention may be made of the
    importance of keeping out cattle, sheep and hogs from the woods, of
    eliminating all insects and disease, of keeping the ground free from
    brush and other inflammable material, of retaining on the ground all
    fallen leaves and keeping the forest well stocked with little trees
    and shrubs.

Forest lands may be exempted from taxation: In New York and other States
    there exists a State law providing for exemption or reduction in
    taxes upon lands which are planted with forest trees or maintained
    as wooded areas. The object of the law is to encourage home forestry
    and to establish fairness in the agricultural land-tax law by
    placing forest lands in the same category with other crop-producing
    lands. For detailed information and a copy of the law, one should
    address the local State Forestry Commission.




CHAPTER VIII

OUR COMMON WOODS: THEIR IDENTIFICATION, PROPERTIES AND USES


Woods have different values for various practical purposes because of
their peculiarities in structure. A knowledge of the structural parts of
wood is therefore necessary as a means of recognizing the wood and of
determining why one piece is stronger, heavier, tougher, or better
adapted for a given service than another.

Structure of wood: If one examines a cross-section of the bole of a
    tree, he will note that it is composed of several distinct parts, as
    shown in Fig. 145. At the very center is a small core of soft tissue
    known as the _pith_. It is of much the same structure as the pith of
    cornstalk or elder, with which all are familiar. At the outside is
    the _bark_, which forms a protective covering over the entire woody
    system. In any but the younger stems, the bark is composed of an
    inner, live layer, and an outer or dead portion.

    Between the pith at the center and the bark at the outside is the
    wood. It will be noted that the portion next to the bark is white or
    yellowish in color. This is the _sapwood_. It is principally through
    the sapwood that the water taken in by the roots is carried up to
    the leaves. In some cases the sapwood is very thin and in others it
    is very thick, depending partly on the kind of tree, and partly on
    its age and vigor. The more leaves on a tree the more sapwood it
    must have to supply them with moisture.

[Illustration: FIG. 144.--Pine Wood. (Magnified 30 times.)]

    Very young trees are all sapwood, but, as they get older, part of
    the wood is no longer needed to carry sap and it becomes
    _heartwood_. Heartwood is darker than the sapwood, sometimes only
    slightly, but in other instances it may vary from a light-brown
    color to jet black. It tends to fill with gums, resins, pigments and
    other substances, but otherwise its structure is the same as that of
    the sapwood.

[Illustration: FIG. 145.--Cross-section of Oak.]

    The wood of all our common trees is produced by a thin layer of
    cells just beneath the bark, the _cambium_. The cambium adds new
    wood on the outside of that previously formed and new bark on the
    inside of the old bark. A tree grows most rapidly in the spring, and
    the wood formed at that time is much lighter, softer and more
    porous than that formed later in the season, which is usually quite
    hard and dense. These two portions, known as _early wood_ or spring
    wood, and _late wood_ or summer wood, together make up one year's
    growth and are for that reason called _annual rings_. Trees such as
    palms and yucca do not grow in this way, but their wood is not
    important enough in this country to warrant a description.

[Illustration: FIG. 146.--White Oak Wood. (Magnified 20 times.)]

    If the end of a piece of oak wood is examined, a number of lines
    will be seen radiating out toward the bark like the spokes in a
    wheel. These are the _medullary rays_. They are present in all
    woods, but only in a few species are they very prominent to the
    unaided eye. These rays produce the "flakes" or "mirrors" that make
    quartersawed (radially cut) wood so beautiful. They are thin plates
    or sheets of cells lying in between the other wood cells. They
    extend out into the inner bark.

    While much may be seen with the unaided eye, better results can be
    secured by the use of a good magnifying glass. The end of the wood
    should be smoothed off with a very sharp knife; a dull one will
    tear and break the cells so that the structure becomes obscured.
    With any good hand lens a great many details will then appear which
    before were not visible. In the case of some woods like oak, ash,
    and chestnut, it will be found that the early wood contains many
    comparatively large openings, called _pores_, as shown in Figs. 146
    and 147. Pores are cross-sections of vessels which are little
    tube-like elements running throughout the tree. The vessels are
    water carriers. A wood with its large pores collected into one row
    or in a single band is said to be _ring-porous_. Fig. 146 shows such
    an arrangement. A wood with its pores scattered throughout the
    year's growth instead of collected in a ring is _diffuse-porous_.
    Maple, as shown in Fig. 152, is of this character.

[Illustration: FIG. 147.--Example of the Black Oak Group. (Quercus
coccinea.) (Magnified 20 times.)]

    All of our broadleaf woods are either ring-porous or diffuse-porous,
    though some of them, like the walnut, are nearly half way between
    the two groups.

    If the wood of hickory, for example, be examined with the magnifying
    lens, it will be seen that there are numerous small pores in the
    late wood, while running parallel with the annual rings are little
    white lines such as are shown in Fig. 149. These are lines of _wood
    parenchyma_. Wood parenchyma is found in all woods, arranged
    sometimes in tangential lines, sometimes surrounding the pores and
    sometimes distributed over the cross-section. The dark, horn-like
    portions of hickory and oak are the _woodfibers_. They give the
    strength to wood.

    In many of the diffuse-porous woods, the pores are too small to be
    seen with the unaided eye, and in some cases they are not very
    distinct even when viewed with a magnifier. It is necessary to study
    such examples closely in order not to confuse them with the woods of
    conifers.

    The woods of conifers are quite different in structure from
    broadleaf woods, though the difference may not always stand out
    prominently. Coniferous woods have no pores, their rays are always
    narrow and inconspicuous, and wood parenchyma is never prominent.
    The woods of the pines, spruces, larches, and Douglas fir differ
    from those of the other conifers in having _resin ducts_, Fig. 144.
    In pines these are readily visible to the naked eye, appearing as
    resinous dots on cross-sections and as pin scratches or dark lines
    on longitudinal surfaces. The presence or absence of resin ducts is
    a very important feature in identifying woods, hence it is very
    important to make a careful search for them when they are not
    readily visible.

How to identify a specimen of wood: The first thing to do in identifying
    a piece of wood is to cut a smooth section at the end and note
    (without the magnifier) the color, the prominence of the rays and
    pores, and any other striking features. If the pores are readily
    visible, the wood is from a broadleaf tree; if the large pores are
    collected in a ring it belongs to the ring-porous division of the
    broadleaf woods. If the rays are quite conspicuous and the wood is
    hard and heavy, it is oak, as the key given later will show. Close
    attention to the details of the key will enable one to decide to
    what group of oaks it belongs.

    In most cases the structure will not stand out so prominently as in
    oak, so that it is necessary to make a careful study with the hand
    lens. If pores appear, their arrangement, both in the early wood and
    in the late wood, should be carefully noted; also whether the pores
    are open or filled with a froth-like substance known as _tyloses_.
    Wood parenchyma lines should be looked for, and if present, the
    arrangement of the lines should be noted.

[Illustration: FIG. 148.--(Magnified about 8 times.)]

    If no pores appear under the magnifying lens, look closely for resin
    ducts. If these are found, note whether they are large or small,
    numerous or scattered, open or closed, lighter or darker than the
    wood. Note also whether the late wood is very heavy and hard,
    showing a decided contrast to the early wood, or fairly soft and
    grading into the early wood without abrupt change. Weigh the piece
    in your hand, smell a fresh-cut surface to detect the odor, if any,
    and taste a chip to see if anything characteristic is discoverable.
    Then turn to the following key:



KEY



I. WOODS WITHOUT PORES--CONIFERS OR SO-CALLED "SOFTWOODS"


A. Woods with resin ducts.

1. Pines. Fig. 144. Resin ducts numerous, prominent, fairly evenly
    distributed. Wood often pitchy. Resinous odor distinct. Clear
    demarcation between heart and sapwood. There are two groups of
    pines--soft and hard.

  (a) Soft Pines. Wood light, soft, not strong, even-textured, very
    easy to work. Change from early wood to late wood is gradual and the
    difference in density is not great.

  (b) Hard Pines. Wood variable but typically rather heavy, hard and
    strong, uneven textured, fairly easy to work. Change from early wood
    to late wood is abrupt and the difference in density and color is
    very marked, consequently alternate layers of light and dark wood
    show. The wood of nearly all pines is very extensively employed in
    construction work and in general carpentry.

2. Douglas fir. Resin ducts less numerous and conspicuous than in the
    pines, irregularly distributed, often in small groups. Odorless or
    nearly so. Heartwood and sapwood distinct. The wood is of two kinds.
    In one the growth rings are narrow and the wood is rather light and
    soft, easy to work, reddish yellow in color; in the other the growth
    rings are wide, the wood is rather hard to work, as there is great
    contrast between the weak early wood and the very dense late wood of
    the annual rings.

    Douglas fir is a tree of great economic importance on the Pacific
    Coast. The wood is much like hard pine both in its appearance and
    its uses.

3. Spruces. Resin ducts few, small, unevenly distributed; appearing
    mostly as white dots. Wood not resinous; odorless. The wood is white
    or very light colored with a silky luster and with little contrast
    between heart and sapwood. It is a great deal like soft pine, though
    lighter in color and with much fewer and smaller resin ducts. The
    wood is used for construction, carpentry, oars, sounding boards for
    musical instruments, and paper pulp.

4. Tamarack. Resin ducts the same as in the spruces. The color of the
    heartwood is yellowish or russet brown; that of the distinct sapwood
    much lighter. The wood is considerably like hard pine, but lacks the
    resinous odor and the resin ducts are much fewer and smaller.

    The wood is used largely for cross-ties, fence posts, telegraph and
    telephone poles, and to a limited extent for lumber in general
    construction.


B. Woods without resin ducts.

1. Hemlock. The wood has a disagreeable, rancid odor, is splintery, not
    resinous, with decided contrast between early and late wood. Color
    light brown with a slight tinge of red, the heart little if any
    darker than the sapwood. Hemlock makes a rather poor lumber which is
    used for general construction, also for cross-ties, and pulp.

2. Balsam fir. Usually odorless, not splintery, not resinous, with
    little contrast between early and late wood. Color white or very
    light brown with a pinkish hue to the late wood. Heartwood little if
    any darker than the sapwood. Closely resembles spruce, from which it
    can be distinguished by its absence of resin ducts.

    The wood is used for paper pulp in mixture with spruce. Also for
    general construction to some extent.

3. Cypress. Odorless except in dark-colored specimens which are somewhat
    rancid. Smooth surface of sound wood looks and feels greasy or waxy.
    Moderate contrast between early and late wood. Color varies from
    straw color to dark brown, often with reddish and greenish tinge.
    Heartwood more deeply colored than the sapwood but without distinct
    boundary line.

    Wood used in general construction, especially in places where
    durability is required; also for shingles, cooperage, posts, and
    poles.

4. Red Cedar. Has a distinct aromatic odor. Wood uniform-textured; late
    wood usually very thin, inconspicuous. Color deep reddish brown or
    purple, becoming dull upon exposure; numerous minute red dots often
    visible under lens. Sapwood white. Red cedar can be distinguished
    from all the other conifers mentioned by the deep color of the wood
    and the very distinct aromatic odor.

    Wood largely used for pencils; also for chests and cabinets, posts,
    and poles. It is very durable in contact with the ground.

    _Western red cedar_ is lighter, softer, less deeply colored and less
    fragrant than the common Eastern cedar. It grows along the Pacific
    Coast and is extensively used for shingles throughout the country.

5. Redwood. Wood odorless and tasteless, uniform-textured, light and
    weak, rather coarse and harsh. Color light cherry. Close inspection
    under lens of a small split surface will reveal many little resin
    masses that appear as rows of black or amber beads which are
    characteristic of this wood.

    Redwood is confined to portions of the Pacific Coast. It is used for
    house construction, interior finish, tanks and flumes, shingles,
    posts, and boxes. It is very durable.



II. WOODS WITH PORES--BROADLEAF, OR SO-CALLED "HARDWOODS"


A. Ring-porous.


1. Woods with a portion of the rays very large and conspicuous.

Oak. The wood of all of the oaks is heavy, hard, and strong. They may be
    separated into two groups. The white oaks and the red or black oaks.

  (a) White oaks. Pores in early wood plugged with tyloses, collected in
    a few rows. Fig. 146. The transition from the large pores to the
    small ones in the late wood is abrupt. The latter are very small,
    numerous, and appear as irregular grayish bands widening toward the
    outer edge of the annual ring. Impossible usually to see into the
    small pores with magnifier.

  (b) Red or black oaks. Pores are usually open though tyloses may
    occur, Fig. 147; the early wood pores are in several rows and the
    transition to the small ones in late wood is gradual. The latter are
    fewer, larger and more distinct than in white oak and it is
    possible to see into them with a hand lens.

    The wood of the oaks is used for all kinds of furniture, interior
    finish, cooperage, vehicles, cross-ties, posts, fuel, and
    construction timber.

2. Woods with none of the rays large and conspicuous.

(a) Pores in late wood small and in radial lines, wood parenchyma in
inconspicuous tangential lines.

Chestnut. Pores in early wood in a broad band, oval in shape, mostly
    free from tyloses. Pores in late wood in flame-like radial white
    patches that are plainly visible without lens. Color medium brown.
    Nearly odorless and tasteless. Chestnut is readily separated from
    oak by its weight and absence of large rays; from black ash by the
    arrangement of the pores in the late wood; from sassafras by the
    arrangement of the pores in the late wood, the less conspicuous
    rays, and the lack of distinct color.

    The wood is used for cross-ties, telegraph and telephone poles,
    posts, furniture, cooperage, and tannin extract. Durable in contact
    with the ground.

(b) Pores in late wood small, not radially arranged, being distributed
singly or in groups. Wood parenchyma around pores or extending wing-like
from pores in late wood, often forming irregular tangential lines.

1. Ash. Pores in early wood in a rather broad band (occasionally
    narrow), oval in shape, see Fig. 148, tyloses present. Color brown
    to white, sometimes with reddish tinge to late wood. Odorless and
    tasteless. There are several species of ash that are classed as
    white ash and one that is called black or brown ash.

  (a) White ash. Wood heavy, hard, strong, mostly light colored except
    in old heartwood, which is reddish. Pores in late wood, especially
    in the outer part of the annual ring, are joined by lines of wood
    parenchyma.

  (b) Black ash. Wood more porous, lighter, softer, weaker, and darker
    colored than white ash. Pores in late wood fewer and larger and
    rarely joined by tangential lines of wood parenchyma.

    The wood of the ashes is used for wagon and carriage stock,
    agricultural implements, oars, furniture, interior finish, and
    cooperage. It is the best wood for bent work.

[Illustration: FIG. 149.--Hickory Wood. (Magnified 45 times.)]

2. Locust. Pores in early wood in a rather narrow band, round, variable
    in size, densely filled with tyloses. Color varying from golden
    yellow to brown, often with greenish hue. Very thin sapwood, white.
    Odorless and almost tasteless. Wood extremely heavy and hard,
    cutting like horn. Locust bears little resemblance to ash, being
    harder, heavier, of a different color, with more distinct rays, and
    with the pores in late wood in larger groups.

    The wood is used for posts, cross-ties, wagon hubs, and insulator
    pins. It is very durable in contact with the ground.

(c) Pores in late wood comparatively large, not in groups or lines.
Wood parenchyma in numerous fine but distinct tangential lines.

[Illustration: FIG. 150.--Elm. (Magnified 25 times.)]

Hickory, Fig. 149. Pores in early wood moderately large, not abundant,
    nearly round, filled with tyloses. Color brown to reddish brown;
    thick sapwood, white. Odorless and tasteless. Wood very heavy, hard,
    and strong. Hickory is readily separated from ash by the fine
    tangential lines of wood parenchyma and from oak by the absence of
    large rays.

    The wood is largely used for vehicles, tool handles, agricultural
    implements, athletic goods, and fuel.

(d) Pores in late wood small and in conspicuous wavy tangential bands.
Wood parenchyma not in tangential lines.

Elm. Pores in early wood not large and mostly in a single row, Fig. 150
    (several rows in slippery elm), round, tyloses present. Color brown,
    often with reddish tinge. Odorless and tasteless. Wood rather heavy
    and hard, tough, often difficult to split. The peculiar arrangement
    of the pores in the late wood readily distinguishes elm from all
    other woods except _hackberry_, from which it may be told by the
    fact that in elm the medullary rays are indistinct, while they are
    quite distinct in hackberry; moreover, the color of hackberry is
    yellow or grayish yellow instead of brown or reddish brown as in
    elm.

    The wood is used principally for slack cooperage; also for hubs,
    baskets, agricultural implements, and fuel.

[Illustration: FIG. 151.--(Magnified about 8 times.)]


B. Diffuse-porous.

1. Pores varying in size from rather large to minute, the largest being
in the early wood. Intermediate between ring-porous and diffuse-porous.

Black Walnut. Color rich dark or chocolate brown. Odor mild but
    characteristic. Tasteless or nearly so. Wood parenchyma in numerous,
    fine tangential lines. Wood heavy and hard, moderately stiff and
    strong. The wood is used principally for furniture, cabinets,
    interior finish, moulding, and gun stocks.

2. Pores all minute or indistinct, evenly distributed throughout annual
ring.

(a) With conspicuously broad rays.

1. Sycamore. Fig. 151. Rays practically all broad. Color light brown,
    often with dark stripes or "feather grain." Wood of medium weight
    and strength, usually cross-grained, difficult to split.

    The wood is used for general construction, woodenware, novelties,
    interior finish, and boxes.

2. Beech. With only a part of the rays broad, the others very fine, Fig.
    151. Color pale reddish brown to white; uniform. Wood heavy, hard,
    strong, usually straight-grained.

    The wood is used for cheap furniture, turnery, cooperage,
    woodenware, novelties, cross-ties, and fuel. Much of it is
    distilled.

(b) Without conspicuously broad rays.

1. Cherry. Rays rather fine but very distinct. Color of wood reddish
    brown. Wood rather heavy, hard, and strong.

    The wood is used for furniture, cabinet work, moulding, interior
    finish, and miscellaneous articles.

2. Maple, Fig. 152. With part of the rays rather broad and conspicuous,
    the others very fine. Color light brown tinged with red. The wood of
    the hard maple is very heavy, hard and strong; that of the soft
    maples is rather light, fairly strong. Maple most closely resembles
    birch, but can be distinguished from it through the fact that in
    maple the rays are considerably more conspicuous than in birch.

    The wood is used for slack cooperage, flooring, interior finish,
    furniture, musical instruments, handles, and destructive
    distillation.

3. Tulip-tree, yellow poplar or whitewood. Rays all fine but distinct.
    Color yellow or brownish yellow; sapwood white. Wood light and soft,
    straight-grained, easy to work.

    The wood is used for boxes, woodenware, tops and bodies of vehicles,
    interior finish, furniture, and pulp.

4. Red or sweet gum. Rays all fine but somewhat less distinct than in
    tulip tree. Color reddish brown, often with irregular dark streaks
    producing a "watered" effect on smooth boards; thick sapwood,
    grayish white. Wood rather heavy, moderately hard, cross-grained,
    difficult to work.

    The best grades of figured red gum resemble Circassian walnut, but
    the latter has much larger pores unevenly distributed and is less
    cross-grained than red gum.

    The wood is used for finishing, flooring, furniture, veneers, slack
    cooperage, boxes, and gun stocks.

[Illustration: FIG. 152.--Maple. (Magnified 25 times.)]

5. Black or sweet birch, Fig. 151. Rays variable in size but all rather
    indistinct. Color brown, tinged with red, often deep and handsome.
    Wood heavy, hard, and strong, straight-grained, readily worked. Is
    darker in color and has less prominent rays than maple.

    The wood is used for furniture, cabinet work, finishing, and
    distillation.

6. Cottonwood. Rays extremely fine and scarcely visible even under lens.
    Color pale dull brown or grayish brown. Wood light, soft, not
    strong, straight-grained, fairly easy to work. Cottonwood can be
    separated from other light and soft woods by the fineness of its
    rays, which is equaled only by willow, which it rather closely
    resembles. The wood is largely used for boxes, general construction,
    lumber, and pulp.



How to judge the quality of wood: To know the name of a piece of wood
    means, in a general way, to know certain qualities that are common
    to all other pieces of wood of that species, but it does not explain
    the special peculiarities of the piece in question or why that
    particular piece is more suitable or unsuitable for a particular
    purpose than another piece of the same species. The mere
    identification of the wood does not explain why a particular piece
    is tougher, stronger or of darker color than another piece of the
    same species or even of the same tree. The reason for these special
    differences lies in the fact that wood is not a homogeneous material
    like metal. Within the same tree different parts vary in quality.
    The heartwood is generally heavier and of deeper color than the
    sapwood. The butt is superior to the top wood, and the manner in
    which the wood was sawed and dried will affect its quality. Knots,
    splits, checks, and discoloration due to incipient decay are defects
    worth considering. Wood that looks lusterless is usually defective,
    because the lack of luster is generally due to disease. Woods that
    are hard wear best. Hardness can be determined readily by striking
    the wood with a hammer and noting the sound produced. A clear,
    ringing sound is a sign of hardness. The strength of a piece of wood
    can be judged by its weight after it is well dried. Heavy woods are
    usually strong. A large amount of late wood is an indication of
    strength and the production of a clear sound when struck with a
    hammer is also an evidence of strength.




CHAPTER IX

AN OUTDOOR LESSON ON TREES


The importance of nature study in the training of the child is now well
recognized. The influences of such study from the hygienic, moral and
aesthetic point of view are far reaching and cannot be expressed in
dollars and cents. In his association with nature, the child is led to
observe more closely and to know and to be fond of what is truly
beautiful in life--beautiful surroundings, beautiful thoughts and
beautiful deeds. He is inspired with reverence for law, order and truth
because he sees it constantly reflected in all works of nature. The
social instinct is highly developed and even the parents are often
bettered through the agency of their children.

The only way, however, to study nature--especially plants--is to study
it out of doors. Our present tendency to gather in cities demands the
upbuilding influences of trips into the open in order to equip the child
mentally and physically to face the world and its work with the strength
and tenacity characteristic of the country-bred. Moreover, the study of
objects rather than books is an axiom in modern education and here, too,
we can readily see that the best way to study trees is to take the pupil
to the trees. Such studies are more lasting than book study because they
emphasize the spirit and the goal rather than the petty facts.

Educators and parents are now recognizing the value of outdoor trips
for their children and are beginning to indulge in them quite
frequently. In many instances teachers about to take out their children
for a day have inquired of the writer how to go about giving a general
field lesson when they reached the park or woodland. The purpose of this
chapter is to answer such a question and yet it is evident that it
cannot be answered completely. What to observe out doors and how to
present one's impressions is a broad question and varies with the
knowledge and ability of the teacher as well as with the age and
experience of the children. The how and the what in nature study is of
greater import than the hard, dry facts and that must be left entirely
to the teacher. A few suggestions, however, may not be amiss:

1. General observations with a view to character building: First of all
    it is important to remember that the great value of all tree and
    nature study is the inculcation in the minds of the children of an
    appreciation and love for the beautiful. Inspiring them to _love_
    trees generally means more than teaching them to _know_ trees. Mere
    facts about trees taught in an academic way are often no more
    lasting than the formulae in trigonometry which most of us have long
    ago forgotten. The important thing is that permanent results be left
    and nothing else will produce such lasting impressions as the study
    of trees out of doors.

[Illustration: FIG. 153.--Trees Have Individuality.]

    General observations about trees can be made by pointing out the
    beauty and character of the individual forms and branching, their
    harmony in their relations to each other as factors of a beautiful
    composition and the wealth of shades and colors in their leaves,
    bark and flowers. Compare, for instance, the intricate ramification
    of an American elm with the simple branching of a sugar maple, the
    sturdiness of a white oak with the tenderness of a soft maple, the
    wide spread of a beech with the slender form of a Lombardy poplar,
    the upward pointing branches of a gingko with the drooping form of a
    weeping willow. At close range, each of these trees reveals itself
    as an individual with a character quite its own. At little distance
    you may see them grouped together, subordinating their individuality
    and helping to blend into a beautiful composition with a character
    all its own. There is nothing more inspiring than the variety of
    greens in the spring foliage, the diversity of color in the spring
    blossoms and the wonderful display of autumnal tints offered by the
    sweet gum, sassafras, dogwood, black gum, red maple, sugar maple,
    scarlet oak, blue beech, sorrel tree, ash and gingko. The white bark
    of the gray birch, the dark bark of the black oak, the gray of the
    beech, the golden yellow of the mulberry and the mottled bark of the
    sycamore are interesting comparisons. The smooth bark of the
    mockernut hickory contrasts greatly with the shaggy bark of the
    shagbark hickory--members of the same family and yet how different.
    A wonderful opportunity is thus offered for a comparative study of
    human nature--individuality and community life, all reflected in
    trees.

    With this preliminary study and with the addition of some remarks on
    the value of trees as health givers and moral uplifters, the child
    is interested and attracted. The lesson so far has attained its aim.

2. Specific observations with a view to training the observative powers:
    The child's training in closeness of observation and scientific
    precision may be the next consideration. His enthusiasm will now
    prompt him to lend his interest for greater detail. We can teach him
    to recognize a few of the common trees by their general
    characters--an American elm by its fan-shaped form, a gray birch by
    its white bark, a white pine by the five needles to each cluster, a
    horsechestnut by its opposite branching and big sticky bud and a
    willow by its drooping habit. After that we may introduce, if the
    age of the pupils justifies, more details extending to greater
    differences which distinguish one species from another.

    The lesson might continue by pointing out the requirements of trees
    for water and light. Find a tree on some slope where the roots are
    exposed and another which is being encroached upon by its neighbor,
    and show how in one case the roots travel in search of water and
    food and in the other the branches bend toward the light, growing
    more vigorously on that side. Compare the trees on the open lawn
    with those in the grove and show how those in the open have grown
    with branches near the ground while those in the woodland are
    slender, tall and free from branches to some distance above the
    ground. Point out the lenticels on the bark of birch and sweet
    cherry trees and explain how trees breathe. Compare this process
    with that of the human body. You may now come across an old stump
    and here you can point out the structure of the wood--the sapwood,
    cambium and bark. You can illustrate the annual rings and count the
    age of the tree. At another point you may find a tree with a wound
    or bruised bark and here you can readily make a closer study of the
    cambium layer and its manner of growth.

    The adaptation of plants to the seasonal changes opens another
    interesting field of study for beginners. If the season is the fall
    or winter, note how the trees have prepared themselves for the
    winter's cold by terminating the flow of sap, by dropping their
    leaves too tender to resist the winter's cold, and by covering their
    buds with scales lined with down on the inside. Observe how the
    insects have spun for themselves silken nests or remain preserved in
    the egg state over the winter. If the season is spring or summer the
    opposite may be noted. See how everything turns to life; how the
    buds are opening, the leaves emerging, the sap running, seeds
    germinating and flowers blooming.

    The soil conditions on the lawn and in the grove furnish another
    interesting feature of comparison and study. In the grove, you can
    demonstrate the decomposition of the fallen leaves, the formation of
    humus and its value to the tree. The importance of the forest soil
    as a conservator of water and its relation to stream flow and soil
    erosion can be brought out at this juncture. An eroded bank and a
    slope covered with trees and shrubs would provide excellent models
    for this study. A consideration of the economic value of the trees
    would also be in place.

3. Civic lessons reflected in trees: The community life of trees in the
    grove, their growth, struggles for light and food and their mutual
    aid can be brought out and compared with the community life among
    people. The trees may here be seen struggling with each other for
    light and food, forcing each other's growth upward, some winning out
    and developing into stalwart and thrifty specimens and others
    becoming suppressed or entirely killed. On the other hand they may
    be seen helping each other in their community growth by protecting
    each other from windfall and by contributing to the fertility of the
    forest soil in dropping their leaves and shading the ground so that
    these fallen leaves may decompose readily.

[Illustration: FIG. 154.--Trees also Grow in Communities.]

4. Enemies of trees: An old stump or tree may be seen crumbling away
    under the influence of fungi and here the children may be shown the
    effects of tree diseases both as destroyers of life and as
    up-builders, because fungi turn to dust the living trees and build
    up others by furnishing them with the decomposed wood matter.

    Insects too, may be invading the old dead tree, and something of
    their nature, habits and influences may be gone into. They may be
    shown as wood borers, leaf eaters, or sap suckers, all injurious to
    the tree. On the other hand they may be shown as seed disseminators
    and as parasites on other injurious insects; all benefactors.

    Forest fires as an enemy of trees might be touched upon by noting
    how easily the leaves may be ignited and a surface fire started when
    the season is dry. Top and ground fires emanating from surface fires
    can then be readily explained.

[Illustration: FIG. 155.--Trees Blend Together to Form a Beautiful
Composition.]

5. Expression: The pupils have by this time been taught to feel the
    beautiful, to observe carefully and to reason intelligently and they
    may now be trained to express themselves properly. This may be
    accomplished by asking them to remember their observations and to
    write about them in the classroom. The lesson may be supplemented
    with effective reading about trees and forests. Interesting reading
    matter of this sort can be found in abundance in children's readers,
    in special books on the subject and in Arbor Day Manuals published
    by the various State Education Departments.

6. Preparation: In order to save time looking for objects of interest
    and for the purpose of correlating the various observations so that
    all will follow in orderly sequence, it is well for the teacher or
    leader to go over the ground beforehand and note the special
    features of interest. The various topics can then be given some
    thought and a brief synopsis can be drawn up to serve as a
    memorandum and guide on the trip.

    It is also well to be provided with a hatchet to cut into some
    decayed stump, a trowel to dig up the forest soil, a knife for
    cutting off twigs and a hand reading glass for examining the
    structural parts of the various objects under observation. A camera
    is always a valuable asset because the photographs hung in the
    classroom become records of great interest to all participants.

7. Suggestions for forming tree clubs: A good way to interest children
    in trees and nature study is to form, among them, a Tree Club. The
    idea has been fully developed in Brooklyn, N.Y., Newark, N.J., and
    other cities and consists of forming clubs of children in the public
    schools and private institutions for the purpose of interesting them
    in the trees around their school and their homes. The members of
    these clubs are each given the tree warden's badge of authority and
    assigned to some special duty in the preservation of the local
    trees. A plan of study and of outdoor trips is laid out for them by
    their director and at stated periods they are given illustrated
    lectures on trees and taken to the neighboring parks or woodlands.




INDEX

Acer negundo,
-- platanoides,
-- polymorphum,
-- pseudoplatanus,
-- rubrum,
-- saccharinum,
-- saccharum,
Aesculus hippocastanum,
-- rubicunda,
Ailing tree, how to tell an,
Air, influence of,
Alternate branched trees,
American beech,
-- elm,
-- larch,
-- linden,
Annual rings,
Aphides or plant lice,
Apple rust,
Arbor-vita and red cedar, description of,
-- (northern white cedar),
Arsenate of lead,
Ash, wood,
-- black,
-- white,
Ash-leaf maple,
Aspen, large-toothed,
--, quaking,
Austrian pine,

Bald cypress,
Balm of Gilead,
Balsam, fir,
--, poplar,
Bark,
Bark, how to prevent splitting when removing branches,
-- or trunk, trees told by their,
Bass-wood,
Bean, Indian,
Beech, American,
--, blue, or hornbeam,
--, copper,
--, European,
-- tree,
Beetle, elm leaf,
Betula alba,
-- lutea,
-- lenta,
-- papyrifera,
-- populifolia,
Bhotan pine,
Bigbud hickory,
Birch, black,
--, European white,
-- fungus rot,
--, gray,
--, paper,
--, sweet,
-- tree,
--, white,
--, yellow,
Bitternut hickory,
Black ash,
-- birch,
-- locust,
-- oak,
-- or sweet birch,
-- spruce,
-- walnut,
Blotches, leaf,
Blue beech, or hornbeam,
-- spruce,
Bolting limbs,
Bordeaux mixture,
Borer, bronze-birch,
--, hickory bark,
--, linden,
--, locust,
--, sugar maple,
Boring insects,
Box-elder,
Bracing limbs, various methods of,
Bracket fungus,
Branches, dead and broken, removal of,
--, how to prevent bark splitting when removing,
Broadleaf or "hardwoods,"
Bronze-birch borer,
Brooklyn, N.Y.,
Broom hickory,
Brown hickory,
Brown-tail moth,
Buckeye,
Butternut,
Buttonball,
Buttonwood,
By-products of forests, utilization of,

Cambium layer,
Camperdown elm,
Care in selecting trees suitable for the soil,
Carolina poplar,
Carpinus caroliniana,
Castanea dentata,
Catalpa speciosa,
Caterpillars,
Caterpillars, leaf-eating,
--, spraying for,
Catkin,
Cattle grazing in forests a source of injury,
Cavities, fungous diseases attacking,
-- how caused,
--, manner of filling,
Cedar apple,
--, white,
Celtis occidentalis,
Chamaecyparis thyoides,
Character building and trees,
Chestnut,
-- and oaks,
-- disease,
Chewing insects,
Cherry,
Child training in observation and precision,
Chlorophyll,
Civic lessons reflected in trees,
Climbing trees, precautions,
Clubs, tree,
Coffee tree,
Colorado blue spruce,
Color of leaves,
Common catalpa,
-- locust,
Community life of trees,
Conifers or "softwoods,"
Coniferous trees,
Copper beech,
Cork elm,
Cornus florida,
Corrosive sublimate,
Cottonwood,
Cottony-maple scale,
Crataegus oxyacantha,
Crown,
Cucumber tree,
Cypress,
-- and larch, description of,
--, bald,
-- knees,
-- obtuse leaf, Japanese,

Dead and broken branches, removal of,
Deciduous trees,
Destroying injurious insects, methods of,
-- pupae,
Developing disease, moisture a factor in,
Diaporthe parasitica,
Diffuse-porous woods,
Disease, fungi as factors of,
-- moisture a factor in developing,
Dogwood, flowering,
Douglas fir,

Effect of heat on trees,
Elkwood,
Elm,
--, American,
--, Camperdown,
--, cork,
--, English,
-- leaf beetle,
--, poplar, gingko and willow trees, told by their form,
--, white,
Enemies of trees,
Enemy of trees, forest fires as an
English elm,
-- hawthorn,
-- yew,
European beech,
-- larch,
-- linden,
-- weeping birch,
-- white birch,


Fall webworm,
Fagus,
-- americana,
-- sylvatica,
Fern, maidenhair,
Fighting forest fires, various ways of,
Filling cavities, manner of,
Fire, guarding woodlands from,
Flowering dogwood,
Foliage, spraying,
Forest fires as an enemy of trees,
-- --, various ways of fighting,
-- lands, exemption from taxation,
--, life and nature of,
-- trees, pruning,
Forestry in various countries,
--, what it is and what it does,
Forests, grazing cattle in, a source of injury,
Forest Service, U.S.,
--, harvesting,
--, harvesting of, to increase production,
--, how established,
--, how harvested,
--, how protected,
--, how they help to regulate streams and prevent floods,
--, method of establishing,
--, planting, with seedling trees,
-- prevent soil erosion,
--, protecting from destructive agencies,
--, safeguarding,
--, utilization of by-products,
Fraxinus americana,
-- nigra,
Frost, effect of, on trees,
Fungi and insects, protection against,
-- as factors of disease,
Fungous diseases attacking cavities,
-- diseases, spraying for,
Fungus, fruiting body of,

Gingko biloba,
-- or maidenhair tree,
Gipsy moth,
Gleditsia triacanthos,
Gloeosporium nervisequum,
Gray or white birch,
Grazing effect on forests,
Grove and lawn, study of soil conditions on,
Gum, red or sweet,
Gymnocladus dioicus,

Hackberry tree,
Hackmatack,
Hard maple,
-- pines,
"Hardwoods," or broadleaf trees,
Hardy catalpa,
Harvesting forests,
Harvesting of forests to increase production,
Hawthorn, English,
Healthy tree, conditions which indicate,
Heartwood,
Heat, effect of, on trees,
Hemlock,
-- and spruce, description of,
Hickory,
-- bark borer,
--, bigbud,
--, bitternut,
--, broom,
--, brown,
--, mockernut,
--, pignut,
--, shagbark,
--, shellbark,
--, whiteheart,
Hicoria alba,
-- glabra,
-- minima,
-- ovata,
Honey locust,
Hop hornbeam,
Hornbeam, (blue beech),
Horsechestnut,
--, red,
Humus,
Hydrophytes,

Important insects,
Improperly pruned trees,
Indian bean,
Individuality of trees,
Insects and fungi, protection against,
--, boring,
--, chewing,
-- galls,
--, important kinds of,
-- injurious to trees,
--, leaf-eating,
--, methods of destroying injurious,
--, nature, habits and influences of,
--, sucking,
--, the four stages, or life history of,
Ironwood tree,
Italian or Lombardy poplar,

Japanese maple,
-- umbrella pine,
Juglans cinerea,
-- nigra,
Juniper,
Juniperus communis,
Juniperus virginiana,

Kerosene emulsion,
Knees, cypress,


Larch, American,
-- and cypress, description of,
-- European,
Large-toothed aspen,
Larix europaea,
Lawn and grove, study of soil conditions on,
Lawn trees,
-- --, pruning,
Leaf blotches,
Leaf-eating caterpillars,
----, insect,
Leaves,
--, needle-shaped,
--, scale-like,
--, star-shaped,
Lenticels,
Leopard moth,
Lesson on trees, outdoor,
Light, influence of, on trees,
Limbs, various methods of bracing,
Lime-sulphur wash,
Lime-tree,
Linden, American,
-- borer,
--, European,
Liquidambar styraciflua,
Liriodendron, tulipifers,
Location of trees, care to be exercised in,
Locust,
--, black,
-- borer,
--, common,
--, honey,
-- miner,
--, yellow,
Lombardy or Italian poplar,
Low juniper,

Magnolia acuminata,
--, mountain,
-- soulangeana,
--, Soulange's,
-- tripetala,
Magnolias, the,
Maiden-hair fern,
-- or gingko tree,
Maple wood,
--, ash-leaf,
--, hard,
--, Japanese,
--, Norway,
-- phenacoccus,
--, red,
--, rock,
--, silver,
--, soft,
-- sugar,
-- swamp,
--, sycamore,
--, white,
Mesophytes,
Method of covering wounds,
Methods of destroying injurious insects,
Mockernut hickory,
Moisture a factor in developing disease,
--, influence of, on trees,
Moral influence of trees,
Morus alba,
-- rubra,
Moth, gipsy,
--, leopard,
Mountain magnolia,
Mugho pine,
Mulberry, red,
--, white,

National forests,
Needle-shaped leaves,
Nettle tree,
Newark, N.J.,
Northern white cedar (arbor-vitae),
Norway maple,
-- spruce,
Nursery, tree,

Oak,
--, black,
--, pin,
--, red,
--, scarlet,
--, swamp white,
--, white,
--, yellow,
Oaks and chestnut,
Observations about trees, general,
-- and precision, child training in,
Obtuse Japanese cypress,
Opposite branched trees,
Orange, Osage,
Oriental spruce,
-- sycamore,
Osage orange,
Ostrya virginiana,
Outdoor lesson on trees,
Oyster-shell scale,

Paper birch,
Picea canadensis,
-- excelsa,
-- mariana,
-- orientalis,
-- parryana,
-- pungens,
Pignut hickory,
Pin oak,
Pine, Austrian,
--, Bhotan,
--, Mugho,
--, red,
--, Scotch,
-- trees,
-- weevil, white,
--, white,
Pines,
Pinus Austriaca,
-- excelsa,
-- mughus,
-- resinosa,
-- rigida,
-- strobus,
-- sylvestris,
Pitch pine,
Pith,
Plane or sycamore tree,
Plant lice, or aphides,
-- study, value of, for children,
-- trees, how to,
Planting forests,
-- forests with seedling trees,
-- little trees, methods of,
--, improving woodland by,
-- new trees,
-- trees,
-- -- most economical method,
-- -- on land unsuitable for crops,
Plants, adaptation of, to seasonal changes,
Platanus occidentalis,
-- orientalis,
Polyporus betulinus,
Poplar, balsam,
--, Carolina,
--, Lombardy or Italian,
--, silver,
--, tulip,
--, white,
--, yellow,
Populus alba,
-- balsamifera,
-- deltoides,
-- grandidentata,
-- nigra,
-- tremuloides,
Pores in wood,
-- small or indistinct,
-- varying in size,
Poster for private woodlands,
Precautions against fire,
Protection against fungi and insects,
Pruning forest trees,
-- lawn trees,
-- shade trees,
--, tools used in,
--, too severe,
-- trees, fundamental principles,
-- --, time for,
Pussy willow,

Quaking aspen,
Quality of trees, how to judge,
Quality of wood, how to judge,
Quercus alba,
-- palustris,
-- platanoides,
-- rubra,
-- velutina,

Red cedar,
-- -- and arbor-vitae, description of,
-- gum,
-- horsechestnut,
-- juniper,
-- maple,
-- mulberry,
-- oak,
-- pine,
-- or black oaks,
-- or sweet gum,
Red spider,
Redwood,
Removal of dead and broken branches,
-- of trees, how to mark,
Requirements of trees,
Retinospora obtusa,
Rhytisma acerinum,
Ring-porous woods,
Robinia pseudacacia,
Rock maple,
Roots,
--, development of,
--, protection of, from drying,
Rust, apple,

Safeguarding forests,
Salix babylonica,
Salix discolor,
Saperda vestita,
Sapwood,
Sawfly,
Scale, cottony-maple,
--, oyster-shell,
Scale-like leaves,
Scarlet oak,
Sciadopitys verticillata,
Scolytus quadrispinosus,
Scotch pine,
Screening trees,
Season, influence of,
Seasons for spraying trees,
Seedling trees, planting forests with,
Shade trees, pruning,
Shagbark hickory,
Shellbark hickory,
Silver maple,
-- poplar,
Soft maple,
-- pines,
"Softwoods" or conifers,
Soil erosion, forests prevent,
--, influence of, on trees,
-- of wooded areas, preserving,
--, physical character of, important for production of trees,
Soulange's magnolia,
Specifications for street tree,
Specimens of wood, how to identify,
Split trees,
Spray trees, how to,
Spraying apparatus,
-- foliage,
-- for caterpillars,
-- for fungous diseases,
-- material,
  arsenate of lead,
  kerosene emulsion,
  lime-sulfur wash,
  tobacco water,
  whale-oil soap,
-- trees, seasons for,
-- trees, thoroughness essential,
Spruce and hemlock, description of,
--, black,
--, blue,
--, Oriental,
--, Norway,
--, white,
Spruces,
Star-shaped leaves,
Stem,
Stomata,
Streets, trees for,
Structure of trees,
-- of woods,
Sucking insects,
Sugarberry,
Sugar maple,
-- maple borer,
Suggestions for forming tree clubs,
-- for outdoor study of trees,
-- for planting little trees,
-- for safety of tree climbers,
-- for tree nursery,
Surface wounds,
Swamp maple,
-- white oak,
Sweet birch,
-- gum,
Sycamore,
-- maple,
-- tree,

Tamarack,
Taxation, forest lands exempt from,
Taxodium distichum,
Taxus baccata,
Thuja occidentalis,
Tilia americana,
-- microphylla,
Tobacco water,
Tools used in pruning,
Toxylon pomiferum,
Training a child to recognize trees,
-- children in observation and precision,
Trametes pini,
Treating surface wounds,
Tree, ailing, how to tell an,
-- and nature study, value of,
--, beech,
--, birch,
--, blue beech,
-- climbers, suggestions for safety of,
-- clubs, suggestions for forming,
--, coffee,
-- diseases,
-- diseases, effects of, as destroyers and up-builders,
-- growth, conditions for, in different localities,
--, hackberry,
--, iron wood,
--, nettle,
-- nursery, suggestions for,
--, plane,
-- repair,
--, sycamore,
--, tulip,
--, weeping willow,
Trees and character building,
--, care of,
--, care to be exercised in location of,
--, civic lessons reflected in,
--, community life of,
--, coniferous,
--, crowding,
--, deciduous,
--, effect of frost on,
--, effect of heat on,
--, enemies of,
-- for lawns,
-- for screening,
-- for streets,
-- for woodland,
--, general observations about,
--, hickories, walnut, and butternut,
--, how to identify,
--, how to mark for removal,
--, how to plant,
--, how to spray,
--, improperly pruned,
--, individuality of
--, influence of light on,
--, influence of moisture on,
--, influence of soil on,
--, insects injurious to,
--, measuring diameter of,
--, methods of planting little,
--, methods of removing,
--, nature and habits of individual,
--, needs that nature or man must supply,
--, outdoor lesson on,
--, physical character of soil important for production of,
--, planting, on land unsuitable for crops,
--, pruning, fundamental principles,
--, --, how to cut properly,
--, quality,
--, rapidity of growth of different species,
--, requirements of,
--, seasons for spraying,
--, setting,
--, structure of,
--, study of rings of various species,
--, suggestions for outdoor study of,
--, suggestions, for planting little,
-- suitable for the soil, care in selecting,
--, tendency to split,
--, thoroughness essential in spraying,
--, time for pruning,
-- told by their bark or trunk,
--, training a child to recognize,
--, value of, as health givers and moral uplifters,
--, what to plant and how,
--, when and how to procure,
--, when to plant,
--, when to spray,
--, wooded areas improved by planting new,
--, yew,
Tsuga canadensis,
Tulip poplar,
-- tree,
Tussock moth,

Ulmus americana,
-- campestris,
Umbrella pine, Japanese,
-- tree,

Value of plant study for children,
-- of tree and nature study,
-- of trees as health givers and moral uplifters,

Walnut,
--, black,
Wasteful lumbering,
Weeping willow tree,
Western catalpa,
Whale-oil soap,
White ash,
-- birch, European,
-- cedar,
-- elm,
-- flowering dogwood,
Whiteheart hickory,
White maple,
-- mulberry,
-- oak,
-- oak, swamp,
-- or gray birch,
-- pine,
-- pine weevil,
-- poplar,
-- spruce,
Whitewood,
Willow, weeping,
--, pussy,
Wood, diffuse-porous,
--, diseased, disposal of,
--, early,
-- fibers,
--, how to identify specimens,
--, how to judge quality of,
--, late,
-- medullary rays,
-- parenchyma,
-- resin ducts,
--, ring-porous,
-- spring,
--, structure, of,
-- summer,
Woodland, care of the,
-- how to improve by removing trees,
-- how to judge, unfavorable conditions,
-- trees,
Woodlands, other means of protecting,
Woodlot, small cost of well-selected young trees for the,
Wood, structure of,
Wooded areas improved by planting new trees,
-- areas, preserving soil of,
Woods, identification, properties and uses of common,
--, ring-porous,
-- with large and conspicuous rays,
-- with pores,
-- with resin ducts,
-- with small and inconspicuous rays,
-- without pores,
-- without resin ducts,
Wounds, importance of covering,
--, methods of covering,
--, treating surface,

Xerophytes,

Yellow birch,
-- locust,
-- oak,
-- poplar,
Yew, English,
Yew trees,
Young trees for the woodlot, small cost of well-selected,





End of Project Gutenberg's Studies of Trees, by Jacob Joshua Levison