A SOUTHERN MICHIGAN WOODLOT

UNIVERSITY BULLETIN

UNIVERSITY OF MICHIGAN
BOTANICAL GARDEN AND ARBORETUM

MICHIGAN TREES

A HANDBOOK OF THE NATIVE AND MOST
IMPORTANT INTRODUCED SPECIES

By
CHARLES HERBERT OTIS, formerly Curator
WITH AN INTRODUCTION BY
GEORGE PLUMER BURNS, formerly Director

Ann Arbor
PUBLISHED BY THE REGENTS
1915

Copyright, 1915
BY
THE REGENTS OF THE UNIVERSITY OF MICHIGAN
THIRD EDITION, REVISED
THE ANN ARBOR PRESS, PRINTERS
ANN ARBOR, MICH.

TABLE OF CONTENTS.

MAP OF MICHIGAN
Showing Only Locations Mentioned in the Manual

INTRODUCTION

The idea of a bulletin on Michigan trees was first suggested by Prof. Volney M. Spalding. It was thought that a bulletin devoted entirely to the study of certain phases of tree life in Michigan would stimulate interest in the study of our trees, and influence many more people to associate themselves with the growing number of tree lovers and with the supporters of the movement for better forest conditions in the state.

The bulletin has been under consideration for a number of years and much of the material given herein has been used in the classes in forest botany at the University of Michigan. It remained, however, for the present Curator of the Botanical Garden and Arboretum to get the material into shape for publication, and the present bulletin is the result of his industry and perseverance. The preparation of the drawings and manuscript has been made by him in connection with his work in the Garden.

The distinctive feature of the bulletin lies in its keys. The keys commonly published are based upon characters which are present but a short time during the year, or which can be used only by an advanced student of botany. This bulletin presents two keys. One is based upon characters which are present all summer; the other uses the winter characters as a basis for identification. By the use of the keys any person should be able to name and learn the characteristics of the trees of Michigan at any time of the year. These keys should prove of special value to our students in the public schools, to members of nature study clubs, and to the students in the forestry schools of the state.

The order of arrangement and the nomenclature are essentially those of “Gray’s New Manual of Botany.” Following a tendency which is steadily gaining favor, all species names are printed with a small letter, regardless of their origin. For the convenience of the general reader, other scientific names which are found in botanical manuals in common use are printed in parenthesis. In the case of exotics which are not included in the Manual, other authorities have been followed. Sudworth’s “Check List of the Forest Trees of the United States” (U. S. Dept. Agr., Div. Forestry, Bul. 17) is in most cases authority for the common names. They are names appearing in common use today in some part of the state. The first name given is that recommended by Sudworth for general use.

The drawings have been made from living or herbarium material and are original. They are accurately drawn to a scale, which is given in each case. In their preparation the author has endeavored to call attention to the salient characters. In the drawings of buds and twigs certain points, bundle-scars, etc., have been emphasized more than is natural. In the descriptions the attempt has been made to bring out those points of similarity and contrast which are most useful for identification.

As the bulletin is not written especially for technical students of botany, the author thought best to use as few technical terms as possible in the descriptions. In some cases it was impossible to avoid such terms, but with the help of the glossary the meaning can be easily understood. Any person desiring to get a more complete knowledge of trees should consult one of the larger manuals. The arrangement used for the illustration and discussion of each single tree makes it possible for the student to compare the drawings with the description without turning a page.

It is believed that with the aid of the drawings and descriptions given in this bulletin any person will be able to name the trees which grow in his yard, park, or woodlot. If, however, any difficulty is found in naming the trees, the Curator will be glad to name any specimens which may be mailed to him. He would be glad to get in touch with persons interested in Michigan trees and to receive any additional information relating to the subject. Data concerning the distribution of the trees in the state, and the addition of other Michigan trees to the present list would be of especial value.

George Plumer Burns.

ACKNOWLEDGMENTS

Grateful acknowledgment is hereby made to Miss Sarah Phelps, who has done most of the inking in and given life to the author’s pencil-drawings; to Mr. J. H. Ehlers for his valuable assistance in the preparation of many of the drawings and in the collection of working material; to Prof. Henri Hus, who has read all of the proof and who has at various times rendered valuable assistance; to Prof. F. C. Newcombe and to Prof. Ernst Bessey for the loan of sheets, from the herbariums of the University of Michigan and Michigan Agricultural College; and especially to Prof. Geo. P. Burns in whose inspiration this bulletin had its inception and under whose direction the work has progressed to completion.

Chas. H. Otis.

HOW TO STUDY THE TREES

People are everywhere associated with trees. Trees give cooling shade in our parks and dooryards and along our highways; they lend their beauty to the landscape and relieve it of monotony; they yield many kinds of fruits, some of which furnish man and the animals of the forest with food; and they furnish vast quantities of lumber for a multitude of uses. How important it is, then, that every person, whether school-child or grown-up, should become acquainted with our trees. Most people know a few of our commonest trees, but are ignorant of the great wealth of tree forms about them. Some who may have wished to go further have been hindered for lack of a teacher or dismayed by the very multitude of manuals to which they have had access.

In beginning a study of the trees the student should start on a solid foundation, eliminating the uncertainties and the errors which no doubt have appeared and retaining only the established facts. Once started he should go slowly, assimilating each new discovery before seeking another. He should begin with the trees nearest home, and, as he gradually grows to know these in all their aspects, should extend his trips afield. Not only should he be able to name the trees when they are fully clothed in their summer dress, but he should as readily know these same trees when the leaves have fallen and only the bare branches stand silhouetted against the sky. Then, and only then, will he derive the utmost satisfaction from his efforts.

The characters which are used in studying the trees are habit, leaves, flowers, fruit, buds, bark, distribution and habitat. These will be discussed briefly in the next few pages, the same order that is used in the detailed descriptions of species being maintained in the present discussion. A few drawings will also be added to make clear certain points and to show comparative forms.

NAME.—Every tree has one or several common names and a scientific or Latin name. Some of these common names are merely local, others have a more extended use. Some few names apply to totally different species. Thus, Cottonwood in Michigan is Populus deltoides, in Idaho and Colorado Populus angustifolia, in California Populus fremontii and in Kentucky Tilia heterophylla. While it should not be forgotten that in common speech it is proper as well as convenient to call trees by their common names, yet, in view of the many uncertainties pertaining to their use, a scientific name is at times absolutely essential to the clear understanding of what is meant. Latin is the language in universal use by all scientists. No longer used by any civilized nation, it has become a dead language and consequently never changes. Its vocabulary and its constructions will a thousand years hence be the same as they are today. Being in universal use among scientists of all nationalities no confusion arises from the use of a Latin word. The Oak in Germany is known as Eiche, in France as chêne and in Spain as roble, but the Latin word Quercus is the same for all these countries.

A scientific name as applied to trees consists of at least two parts, as Quercus alba; the first named is the genus and is always written with a capital letter, the second is the species and is written with a small letter, the two names constituting the briefest possible description of the particular tree. It is customary to add to these the name or an abbreviation of the name of the person who first gave the name to the tree, as Quercus alba L., the abbreviation standing for Linnaeus. Sometimes a third name is used, as Acer saccharum nigrum, referring in this case to a variety of the ordinary Sugar Maple.

Genera which bear a relationship to each other are placed in the same family, the family name always having the characteristic ending—aceae. Related families are again grouped into orders, with the characteristic ending—ales. Orders are in like manner arranged into larger groups, called classes, and the latter into still larger groups, divisions, etc., each with its characteristic ending. Thus, Acer saccharum nigrum (Michx. f.) Britt. is classified as follows:

Division—Spermatophyta
Subdivision—Angiospermae
Class—Dicotyledoneae
Order—Sapindales
Family—Aceraceae
Genus—Acer
Species—saccharum
Variety—nigrum.

HABIT.—Habit, or the general appearance of a plant, is an important character of identification, especially as we become more and more familiar with the trees. Two main types are recognized, based on the manner of branching of the trunk, the upright and the spreading. In the one the trunk extends straight upwards without dividing, as is typical in most of the conifers, and in the other the trunk divides to form several large branches and the broad, spreading crown of most of our broad-leaf trees. The crown in either case may be regular in outline or very irregular, straggling or straight-limbed. Moreover, the tree growing in the open, where there is no crowding and there is plenty of light, may differ very greatly from the tree in the forest, where the struggle for existence becomes very keen. A short, thick trunk and low, spreading, many-branched crown characterizes the tree in the open, whereas the forest tree has a long, slender, clean trunk and a narrow crown of few branches. In the descriptions of trees in this bulletin, unless otherwise stated, the habit in the open is the one given. Again, the tree may have been injured by storm or insect at some period of its growth and its natural symmetry destroyed. Moreover, the age of a tree has a great influence on its outline, young trees being generally narrow and more or less conical, broadening out as they become older. We may say, then, that each tree has an individuality of its own, little eccentricities similar to those that make people different from one another. And just as we have little difficulty in recognizing our friends at a distance by some peculiarity of walk or action, so are we able to recognize a great many trees at a distance by some peculiarity of form or habit.

I. LEAF OUTLINES

II. LEAF TIPS

LEAVES.—With the advent of spring the buds of our broad-leaf trees swell and burst and the leaves come forth and clothe the trees with mantles of green, hiding the branches which have been bare through the cold winter months. The evergreens, too, take on new color and begin a new period of growth. It is the leaves which the beginner finds most interesting and in which he finds a ready means of identification. It must be remembered, however, that leaves vary greatly in size and shape and general appearance. How large are the leaves on a flourishing sprout and how small on a stunted tree of the same species growing near by, but under adverse circumstances. How different are the leaves of the big white oak standing in the yard; they are hardly lobed on the lowermost branches, while higher up they are deeply cut. Yet, in spite of the many modifications that leaves undergo, the leaves of any one species have certain rather constant characters which are found in all forms, and the student will have little difficulty in selecting and recognizing typical leaves.

III. LEAF MARGINS

Serrate. Doubly Serrate. Crenate. Undulate. Sinuate. Lobed. Dentate.

Leaves are either persistent, as in most of our conifers, which stay green all winter, or they turn various colors with the frost and fall early in autumn; often they hang dead and lifeless far into the winter. The points about leaves which we are accustomed to consider are the position or arrangement of the leaves on the branch, whether simple or compound, size, shape, texture, color, amount and character of pubescence, character of the margin, venation, etc. The following diagrams will serve to illustrate some of the ordinary forms and shapes of leaves, their margins, etc.

IV. PARTS OF A FLOWER

Perfect Flower. Stamen. Pistil.

FLOWERS.—Every tree when old enough bears flowers in its proper season. Some of these, as the Catalpas, Locusts and Horse-chestnuts are very showy, others, like the Oaks and Hickories, are comparatively inconspicuous; some are brilliantly colored, others are of the same color as the leaves. Nevertheless, the flowers are very accurate means of classification, and their only drawback is that they last for such a short period of time each year.

Just as we have male and female in the animal world, so we have male and female in the plant world. A few of our trees, as the Locust, Basswood and Cherries have perfect flowers, bearing both stamens and pistil. The great majority, however, have unisexual flowers, bearing stamens or pistils, but not both. When both male and female flowers are found on the same tree, the flowers are said to be monoecious, and when male flowers occur on one tree and the female on a different tree, the flowers are said to be dioecious. The Cottonwood is dioecious, and the little seeds are surrounded by a tuft of long, white hairs which enables the wind to carry them to considerable distances from the parent tree, to the disgust of people living within range. Many cities forbid the planting of Cottonwood on account of the “cotton.” Since in some cases it is desirable to plant this rapid-growing tree, as in cities burning large amounts of soft coal, it is a distinct advantage to know that male trees are lacking in the objectionable “cotton” and may be planted safely.

V. TYPES OF INFLORESCENSES

Before trees can produce fruit their flowers must be fertilized, i.e., pollen from the anther of a stamen must come in contact with the stigma of a pistil. Some flowers are self-fertilized, others are cross-fertilized. For a long time it was not known how fertilization was accomplished, but now we know that many insects, like the nectar-loving bees and butterflies, and in other cases the wind transport the pollen from one flower to another, often miles being traversed before the right kind of flower or a flower in the right stage of development is found. And many are the modifications of flowers to insure this transference of pollen.

FRUIT.—So numerous and so varied are the forms of tree fruits that it would only be confusing to enumerate their various characters. Some fruits, as the achenes of the Poplars and Willows, are so small and light that they are carried long distances by the wind; others, like the hickory nuts and walnuts, are too heavy to be wind-blown. Many fruits are of considerable economic and commercial importance and are gathered and marketed on a large scale; such are the hickory nuts, walnuts, chestnuts, etc. Some, not esteemed by man, form an important article of diet for the birds and small animals of the forest. Unfortunately, there are a number of limitations to the usefulness of fruit for identification purposes. Some trees require years to mature their fruit. Many trees, while producing an abundance of fruit at certain intervals, bear none at all or only very small and uncertain quantities between the years of abundance. Again, in the case of dioecious trees, only the female or pistillate bear fruit. Notwithstanding these limitations tree fruits are a very valuable aid to the student, and he should always search closely for evidences of their presence and character.

VI. WINTER
TWIG OF RED
MULBERRY

a. Tip-scar.
b. Lateral bud.
c. Leaf-scar.
d. Stipule-scars.

WINTER-BUDS.—Buds, with their accompanying leaf-and stipule-scars form the basis of tree identification in winter. The size, color, position with reference to the twig, number and arrangement and character of bud-scales, etc., are all characters of the greatest value in winter determinations. Buds are either terminal or lateral, depending on their position on the twig. A lateral bud is one situated on the side of a twig in the axil of a leaf-scar. A terminal bud is one situated at the end of a twig, where it is ready to continue the growth of the twig the following spring. In the keys an important consideration is the presence or absence of the terminal bud. Inasmuch as the determination of this point gives the beginner some trouble at first, it is hoped that the accompanying diagrams and explanatory remarks will make the distinction clear.

VII. WINTER
TWIG OF BLACK
WALNUT

a. Terminal bud.
b. Lateral bud.
c. Leaf-scar.
d. Bundle-scars.
e. Pith.

In the Elms, Willows, Basswood and many other species the terminal bud and a small portion of the tip of the twig dies and drops off in late autumn, leaving a small scar at the end of the twig (a, fig. VI). The presence of this tip-scar indicates that the terminal bud is absent. Often a lateral bud will be found very close to the tip-scar (b, fig. VI), which, bending into line with the twig, makes it appear terminal. However, the presence of a leaf-scar immediately below it shows it to be a lateral bud (c, fig. VI). In some large twigs the eye unaided will serve to find the tip-scar, but with the smaller twigs a hand-lens is necessary.

The arrangement, size and shape of the leaf-scars (c, fig. VII) are important factors in identification by winter characters. Within the leaf-scars are one or more dots (d, fig. VII), sometimes quite inconspicuous, often very prominent. These are the scars left by the fibro-vascular bundles which run through the petiole into the blade of the leaf, and are designated as bundle-scars. There may be only one as in Sassafras and Hackberry, two as in Ginkgo, three as in the Poplars and Cherries, or many; and they may be arranged in a U- or V-shaped line, or they may be without definite order. Often stipule-scars (d, fig. VI) occur on either side of the leaf-scar; these are scars left by the fall of a pair of small leaflets called stipules and located at the base of the leaves, and their form varies according to the form of the stipules which made them.

BARK.—The woodsman uses the bark of a tree more than any other character in distinguishing the trees about him, and he is often able to use this character alone with much accuracy at great distances. However, the appearance of bark differs so greatly with the age of the tree and with its environment that it is difficult to describe it accurately. Some characters are distinctive, however, and serve as a ready means of identification; such characters are the peeling of the Sycamore and Paper Birch, the “shagging” of the Shagbark Hickory, the spicy taste of Sassafras bark and the mucilaginous inner bark of the Slippery Elm.

WOOD.—It is not expected that the information given under this heading will be of any particular value in identifying living trees. Often, however, the student finds himself in the midst of felling operations, when the information concerning the wood is of considerable value.

DISTRIBUTION AND HABITAT.—To a lesser extent do distribution and habitat of a species aid in the identification of a tree. It is a distinct aid to know that the Chestnut is native in south-eastern Michigan only and that the Mountain Ash does not extend south of Ludington. So too, knowing the water-loving habit of the Swamp White Oak, we would not expect to find this same tree flourishing on the top of a hard, dry hill.

The characters, then, which are used to identify the trees about us are many. Not all will be available at any one time, not all have been mentioned in the foregoing pages nor in the manual. It is our opinion, however, that the student will not be greatly handicapped by this lack of detail, but rather that he will take great interest and genuine pleasure in discovering these things for himself.

ARTIFICIAL KEYS, HOW MADE AND USED

An artificial key is a scheme for easily and quickly identifying any unknown object under consideration. This bulletin being devoted to the trees of Michigan, the keys to be found herein are intended to make it possible for any person, even if his botanical training be meager, to determine what trees grow about any home or farm, city park or woodlot in the state. With certain modifications and limitations they may prove useful in other localities as well. Since many people are unfamiliar with the construction and use of keys for identification, it will be the purpose of the following paragraphs to briefly outline the principles of construction and the manner of using the keys to be found here.

The keys are based on the most striking similarities and differences which the various parts of trees—twigs, buds, leaves, etc.—show, i. e., those characters which stand out in bold relief, which catch the eye at first sight. Two alternatives are presented, either a character is or is not present; these are the only choices possible. Indeed, further divisions are unnecessary and only lead to confusion and possible oversight. The two diametrically opposed characters are said to be coördinate in rank. In the keys they are preceded by the same letter or letters (a and aa or b and bb, etc.) and are set at the same distance from the left margin of the page. Often a and aa, or b and bb are further divisible into other groups; in every case the characters are opposed (a positive and a negative) and are given coördinate rank. It is desirable for mechanical reasons to divide the main divisions of the key more or less evenly, but this is not always feasible, nor should it be religiously adhered to.

Suppose as a concrete example that it is desired to construct a key to distinguish five houses in a city block. Three of these are of wood construction, two are of brick, and of the two wooden houses one is painted white and one brown. We may classify them as follows:

It is desirable in many cases to add other characters to lessen the liability of confusion, where the characters chosen are not distinct, and to show the user that he is on the right track. Thus, in the example just given, green color and slate color under certain defects of the eye, a coating of dust or deficiencies of the light might be confused, under which circumstances we would be justified in adding to the above statements without the criticism of description being made. Thus:

The keys in this bulletin are constructed on the above principles. They are not in all cases as simple as the illustration just used, but if the reader has mastered the house illustration he will have little or no trouble with the larger keys. Suppose that (during a summer stroll) you come across a large tree with rough, hard bark and thin, lobed leaves which you do not know. Turning to the Summer Key to the Genera you find first a. Leaves simple, and contrasted with this aa. Leaves compound. Obviously the leaf is simple and the genus sought lies in that portion of the key preceding aa, i.e., under a. b and bb under a give you a choice between Leaves needle-shaped, awl-shaped, strap-shaped or scale-like and Leaves broad and flat. The leaf being broad and flat you pass to c and cc under bb. Here you have a choice between Leaves alternate or clustered and Leaves opposite or whorled. Inspection shows the arrangement to be opposite, and you know that the genus sought lies in that portion of the key between cc and aa. Passing to d and dd under cc gives the choice between Margin of leaves entire or only slightly undulate and Margin of leaves serrate to lobed. The leaf is deeply lobed. It is then either a Viburnum or an Acer, and the fact that the leaf-margin is lobed and not finely serrate brings the chase down to Acer. Before going further go back over the key and make careful note of the particular characters which were used to separate this genus from the other genera and try to fix these in mind. This done, turn to the page indicated, where you will find a Summer Key to the Species of Acer. You run through this key in the same manner that you did the genus key. If you have been careful in your search you will finally stop at Acer saccharum. Once more pause and go back over this key and try to fix in mind the characters which were used to separate the various species, especially the difference between your tree and Acer platanoides, which it so closely resembles. This done, turn to the page indicated and compare the characters of your tree with the drawings and descriptions. If you are satisfied with your diagnosis, well and good. If you find that you are wrong, go over the keys again and find wherein you were led astray.

Before you leave the tree take a sample of leaf properly labeled which you can press between the pages of an old magazine and save for future reference. Do this with other trees which you may find and when you get home lay them out side by side so that the labels will not show and compare them. A few trials of this kind will serve to form a mental picture of each leaf which you will remember.

A very helpful practice for the beginner is that of making keys based upon various characters. Practice keys of this kind will bring out the differences and likenesses of trees as will no other means, and characters which have hitherto escaped the eye will be prominently brought forward. Nor should the student take his characters from books, but rather should he go to the woods and get his knowledge first hand.

It is hardly necessary to state that the key is a valuable crutch while learning to walk, but once the leg is strong enough to bear the weight it should be discarded, lest it become a burden. A key has for its main object the guidance of the student through the preliminary steps leading to a more intimate knowledge of the trees. When once he knows a tree, instinctively, because of long acquaintance with it, just as he knows people, then the need for a key will have ceased.

SUMMER KEY TO THE GENERA [A]

WINTER KEY TO THE GENERA[B]

MANUAL OF TREES

DESCRIPTION OF SPECIES

WITH

SUMMER AND WINTER KEYS
TO THE SPECIES

GINKGOACEAE

Ginkgo. Maidenhair Tree

1. Winter twig, × 1/2.

2. Leaf, × 1/2.

3. Staminate flowering branchlet, × 1/2.

4. Staminate flower, enlarged.

5. Pistillate flower, enlarged.

6. Fruit, × 1.

GINKGOACEAE

Ginkgo.[C] Maidenhair Tree

Ginkgo biloba L. [Salisburia adiantifolia Smith]

HABIT.—A slender tree in youth, with slender, upright branches, becoming broader with age and forming a symmetrical, pyramidal crown; probably 60-80 feet high, with a trunk diameter of 2-4 feet.

LEAVES.—Clustered at the ends of short, spur-like shoots, or scattered alternately on the long terminal branches; simple; 2-5 inches broad; more or less fan-shaped; usually bilobed and irregularly crenate at the upper extremity; thin and leathery; glabrous, pale yellow-green on both sides; petioles long, slender; turning a clear, golden yellow before falling in autumn.

FLOWERS.—May, with the leaves; dioecious; the staminate in short-stalked, pendulous catkins, 1 to 1-1/2 inches long, yellow; the pistillate more or less erect on the shoot, long-stalked, consisting of 2 naked ovules, one of which usually aborts.

FRUIT.—Autumn; a more or less globose drupe, orange-yellow to green, about 1 inch in diameter, consisting of an acrid, foul-smelling pulp inclosing a smooth, whitish, somewhat flattened, almond-flavored nut.

WINTER-BUDS.—Terminal bud about 1/8 inch long, conical, smooth, light chestnut-brown; lateral buds divergent, usually only on rapid-growing shoots.

BARK.—Twigs gray-brown and smooth; thick, ash-gray and somewhat roughened on the trunk, becoming more or less fissured in old age.

WOOD.—Light, soft, weak, close-grained, yellow-white to light red-brown, with thin, lighter colored sapwood.

NOTES.—Origin in dispute, but probably a native of northern China. Extensively cultivated in China and Japan, where its fruit is esteemed. Easily propagated from seed. Thrives in deep, well-drained, rich soil. Practically free from insect and fungous attacks, and little harmed by the smoke of cities. Probably hardy throughout the southern half of the Lower Peninsula.

PINACEAE

SUMMER KEY TO THE SPECIES OF PINUS

WINTER KEY TO THE SPECIES OF PINUS

White Pine

1. Cluster of leaves, × 1.

2. Cross-sections of leaves, enlarged.

3. Partly opened cone, × 3/4.

4. Cone-scale with seeds, × 1.

PINACEAE

White Pine

Pinus strobus L.

HABIT.—A large tree 60-80 feet high, with a trunk diameter of 2-4 feet; forming a wide, pyramidal crown. Formerly trees 100-150 feet in height and 5-7 feet in trunk diameter were not exceptional.

LEAVES.—In clusters of five; 3-5 inches long; slender, straight, needle-shaped, 3-sided, mucronate; pale blue-green. Persistent about 2 years.

FLOWERS.—June; monoecious; the staminate oval, light brown, about 1/3 inch long, surrounded by 6-8 involucral bracts; the pistillate cylindrical, about 1/4 inch long, pinkish purple, long-stalked.

FRUIT.—Autumn of second season, falling during the winter and succeeding spring; pendent, short-stalked, narrow-cylindrical, often curved, greenish cones, 4-10 inches long; scales rather loose, slightly thickened at the apex; seeds red-brown, 1/4 inch long, with wings 1 inch long.

WINTER-BUDS.—Oblong-ovoid, sharp-pointed, yellow-brown, 1/4-1/2 inch long.

BARK.—Twigs at first rusty-tomentose, later smooth and light brown, finally thin, smooth, greenish; thick, dark gray on the trunk, shallowly fissured into broad, scaly ridges.

WOOD.—Light, soft, weak, compact, straight-grained, easily worked, light brown, with thin, whitish sapwood.

DISTRIBUTION.—Upper Peninsula and Lower Peninsula north of Allegan, Eaton and St. Clair Counties. Often planted as an ornamental tree farther south.

HABITAT.—Prefers a light, fertile loam; sandy soils of granite origin.

NOTES.—Rapid of growth. Small seedlings easily transplanted. Formerly very abundant, but rapidly nearing extinction through destructive lumbering.

Jack Pine. Scrub Pine

1. Cluster of leaves, × 1.

2. Cross-section of leaf, enlarged.

3. Branchlet with unopened cone, × 1.

4. Branchlet with opened cone, × 1.

5. Cone-scale with seeds, × 1.

PINACEAE

Jack Pine. Scrub Pine

Pinus banksiana Lamb. [Pinus divaricata (Ait.) Du Mont de Cours.]

HABIT.—Usually a small tree 20-30 feet high, with a trunk diameter of 8-12 inches; forming a crown varying from open and symmetrical to scrubby, stunted, and variously distorted.

LEAVES.—In clusters of two; about 1 inch long; narrow-linear, with sharp-pointed apex; stout, curved or twisted, divergent from a short sheath; dark gray-green. Persistent 2-3 years.

FLOWERS.—May-June; monoecious; the staminate in oblong clusters 1/2 inch long, composed of many sessile, yellow anthers imbricated upon a central axis; the pistillate in subglobose clusters, composed of many carpel-like, purple scales (subtended by small bracts) spirally arranged upon a central axis.

FRUIT.—Autumn of second or third season, but remaining closed for several years and persistent on the tree for 10-15 years; erect, usually incurved, oblong-conical, sessile cones, 1-1/2-2 inches long; scales thickened at the apex; seeds triangular, nearly black, 3/8 inch long, with wings 1/3 inch long.

WINTER-BUDS.—Terminal bud 1/4 inch long, ovoid, rounded, pale brown; lateral buds smaller.

BARK.—Twigs yellow-green, becoming purple, finally dark red-brown and rough with the persistent bases of fallen leaves; thin, dark red-brown on the trunk, with shallow, rounded ridges, rough-scaly on the surface.

WOOD.—Light, soft, weak, close-grained, light brown, with thick, whitish sapwood.

DISTRIBUTION.—Common from Clare County northward; occurs sparingly along the lake shore as far south as Grand Haven on the west and Port Austin on the east.

HABITAT—Sandy, sterile soil.

NOTES.—Cones open unevenly. Slow of growth. Difficult to transplant.

Austrian Pine. Black Pine

1. Cluster of leaves, × 1.

2. Cross-section of leaf, enlarged.

3. Unopened cone, × 1.

4. Partly opened cone, × 1/2.

5. Cone-scale with seeds, × 1.

PINACEAE

Austrian Pine. Black Pine

Pinus laricio austriaca Endl. [Pinus austriaca Höss.]

HABIT.—A large tree 60-80 feet high, with a trunk diameter of 2-4 feet; forming a massive, spreading crown of stiff, strong branches.

LEAVES.—In clusters of two; 3-6 inches long; slender, rigid, sharp-pointed, curved towards the twig; deep green on both faces. Persistent 3-6 years.

FLOWERS.—May-June; monoecious; the staminate cylindrical, subsessile, bright yellow, about 3/4 inch long; the pistillate cylindrical, small, bright red, subsessile.

FRUIT.—Autumn of first season, opening two years after full size is attained and remaining on the tree several years; erect, sessile, long-ovoid cones 2-3 inches long; scales smooth, lustrous, thickened at the apex and topped with a short spine in the center; seeds red-brown, 1/4 inch long, with wings 3/4 inch long.

WINTER-BUDS.—Oblong-conical, sharp-pointed, red-brown, resinous, about 1/2 inch long.

BARK.—Twigs brownish to olive-brown and smooth, becoming darker with age; thick, gray to nearly black on old trunks and coarsely and deeply fissured.

WOOD.—Light, strong, very resinous, red-brown, with thick, yellowish to reddish white sapwood.

NOTES.—Perfectly hardy. Adapts itself to a variety of soils. Well adapted for screens and wind-breaks. Easily transplanted when small. Grows rapidly.

Scotch Pine. Scotch Fir

1. Cluster of leaves, × 1.

2. Cross-section of leaf, enlarged.

3. Unopened cone, × 1.

4. Partly opened cone, × 1.

5. Cone-scale with seeds, × 1.

PINACEAE

Scotch Pine. Scotch Fir

Pinus sylvestris L.

HABIT.—A large tree 60-80 feet high, with a trunk diameter of 1-2 feet; the side branches persist, forming a massive, wide-spreading crown.

LEAVES.—In clusters of two; 1-1/2-3 inches long; stiff, more or less twisted, spreading slightly from a short sheath; bluish- or often glaucous-green. Persistent 3-4 years.

FLOWERS.—May-June; monoecious; the staminate ovoid, short-stalked, yellowish, about 1/4 inch long; the pistillate oblong, reddish, short-stalked, about 1/4 inch long.

FRUIT.—Autumn of second season, falling as soon as ripe; pendent, stout-stalked, ovoid-conical cones 1-1/2-2-1/2 inches long; scales dull gray-brown, thickened at the apex into 4-sided, recurved points; seeds red-brown, nearly 1/4 inch long, with wings about 3/4 inch long.

WINTER-BUDS.—Oblong-ovoid, sharp-pointed, red-brown, resinous, about 1/4 inch long.

BARK.—Twigs reddish to orange-brown, becoming grayish; thick, dark orange-brown on old trunks and coarsely and deeply fissured.

WOOD.—Light, stiff, straight-grained, strong, heavy, hard, resinous, red-brown, with thick, yellow to reddish white sapwood.

NOTES.—Very rapid of growth. Reaches perfection only in cold or elevated regions. Adapts itself to a variety of soils. A valuable ornamental tree. Very useful for screens or shelter belts.

Red Pine, Norway Pine

1. Cluster of leaves, × 1.

2. Cross-section of leaf, enlarged.

3. Opened cone, × 1.

4. Cone-scale with seeds, × 1.

PINACEAE

Red Pine. Norway Pine

Pinus resinosa Ait.

HABIT.—A large tree 70-80 feet high, with a trunk diameter of 2-3 feet; stout, horizontal branches, form a broad, rounded, rather open crown.

LEAVES.—In clusters of two; 4-6 inches long; slender, straight, needle-shaped, sharp-pointed, flexible, from elongated, persistent sheaths; lustrous dark green. Persistent 4-5 years.

FLOWERS.—April-May; monoecious; the staminate in oblong, dense clusters, 1/2-3/4 inch long, composed of many sessile, purple anthers imbricated upon a central axis; the pistillate single or few-clustered at the end of the branchlets, subglobose; scales ovate, scarlet, borne on stout peduncles covered with pale brown bracts.

FRUIT.—Autumn of second season, falling the next summer; ovoid-conical, nearly sessile cones, about 2 inches long; scales thickened at the apex; seeds oval, compressed, light mottled-brown, with wings 1/2-3/4 inch long.

WINTER-BUDS.—About 3/4 inch long, ovoid or conical, acute, red-brown, with rather loose scales.

BARK.—Twigs orange-brown, becoming rough with the persistent bases of leaf-buds; thick and red-brown on the trunk, shallowly fissured into broad, flat ridges.

WOOD.—Light, hard, very close-grained, pale red, with thin, yellow to white sapwood.

DISTRIBUTION.—Very abundant in Clare County and northward; frequent on the east side of the state as far south as Port Huron.

HABITAT.—Sandy plains and dry woods.

NOTES.—Rapid of growth on the better soils. Difficult to transplant.

Tamarack

1. Autumn branchlet, with leaves and cones, × 1.

2. Cross-section of leaf, enlarged.

3. Fruiting branchlet in winter, × 1.

4. Cone-scale with seeds, × 2.

PINACEAE

Tamarack

Larix laricina (DuRoi) Koch [Larix americana Michx.]

HABIT.—A tree sometimes 80-100 feet high, with a trunk diameter of 1-2 feet; forming a broad, open, irregular crown of horizontal branches.

LEAVES.—Scattered singly along the leading shoots or clustered on the short lateral branchlets; linear, with blunt apex; rounded above, keeled beneath; about 1 inch long; bright green; sessile. Deciduous in early autumn.

FLOWERS.—April-May, with the leaves, monoecious; the staminate sessile, subglobose, yellow, composed of many short-stalked anthers spirally arranged about a central axis; the pistillate oblong, short-stalked, composed of orbicular, green scales (subtended by red bracts) spirally arranged about a central axis.

FRUIT.—Autumn of first season, but persistent on the tree for a year longer; ovoid, obtuse, light brown, short-stalked cones, 1/2-3/4 inch long; seeds 1/8 inch long, with pale brown wings widest near the middle.

WINTER-BUDS.—Small, globose, lustrous, dark red.

BARK.—Twigs at first grayish, glaucous, later light orange-brown, and finally dark brown; red-brown and scaly on the trunk.

WOOD.—Heavy, hard, very strong, coarse-grained, very durable, light brown, with thin, nearly white sapwood.

DISTRIBUTION.—Common throughout the state.

HABITAT.—Prefers cold, deep swamps, or in the north coming out on the drier uplands.

NOTES.—Becomes a picturesque tree in old age. Should be transplanted while dormant.

SUMMER KEY TO THE SPECIES OF PICEA

WINTER KEY TO THE SPECIES OF PICEA

White Spruce

1. Winter branchlet, x.

2. Leaves, × 1.

3. Cross-section of leaf, enlarged.

4. Unopened cone, × 1.

5. Partly opened cone, × 1.

6. Cone-scale with seeds, × 1.