The Project Gutenberg EBook of Michigan Trees, by Charles Herbert Otis This eBook is for the use of anyone anywhere at no cost and with almost no restrictions whatsoever. You may copy it, give it away or re-use it under the terms of the Project Gutenberg License included with this eBook or online at www.gutenberg.org Title: Michigan Trees A Handbook of the Native and Most Important Introduced Species Author: Charles Herbert Otis Contributor: George Plumer Burns Release Date: November 17, 2012 [EBook #41394] Language: English Character set encoding: ISO-8859-1 *** START OF THIS PROJECT GUTENBERG EBOOK MICHIGAN TREES *** Produced by Marilynda Fraser-Cunliffe, Turgut Dincer and the Online Distributed Proofreading Team at http://www.pgdp.net A SOUTHERN MICHIGAN WOODLOT A SOUTHERN MICHIGAN WOODLOT UNIVERSITY BULLETIN NEW SERIES, SEPTEMBER, 1915 VOL. XVII, NO. 10 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 printer's mark 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. PAGE A Southern Michigan Woodlot—Frontispiece. Map of Michigan (Showing Details Mentioned in the Bulletin) iv Introduction v Acknowledgments vii How to Study the Trees ix Artificial Keys, How Made and Used xviii Summer Key to the Genera xxi Winter Key to the Genera xxvii Manual of Trees (Description of Species, with Summer and Winter Keys to the Species) 1 GINKGOACEAE 2 PINACEAE 4 SALICACEAE 34 JUGLANDACEAE 60 BETULACEAE 80 FAGACEAE 92 URTICACEAE 122 MAGNOLIACEAE 136 LAURACEAE 138 PLATANACEAE 140 ROSACEAE 142 LEGUMINOSAE 162 SIMARUBACEAE 170 ACERACEAE 172 SAPINDACEAE 194 TILIACEAE 200 CORNACEAE 202 OLEACEAE 210 BIGNONIACEAE 222 CAPRIFOLIACEAE 228 Glossary 231 Index to the Artificial Keys 241 Index to the Trees 242 [Pg iii] [Pg iv] MAP OF MICHIGAN 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, [Pg v] [Pg vi] 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 [Pg vii] [Pg viii] [Pg ix] [Pg x] 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 Lanceolate. Ovate. Heart-shaped. Halberd-shaped. Elliptical. Lanceolate. Ovate. Heart-shaped. Halberd-shaped. Linear. Elliptical. Oblong. Oval. Orbicular. Spatulate. Obovate. Oblong. Oval. Orbicular. Oblanceolate. Spatulate. Obovate. II. LEAF TIPS Acute. Obtuse. Emarginate. Mucronate. Acuminate. Acute. Obtuse. Emarginate. Mucronate. [Pg xi] IV. PARTS OF A FLOWER Perfect Flower. Stamen. Pistil. Perfect Flower. Stamen. Pistil. a. Sepal (Calyx). f. Filament. b. Petal (Corolla). g. Stigma. c. Stamen. h. Style. d. Pistil. i. Ovary. e. Anther. 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 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. 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 Raceme. Panicle. Corymb. Umbel. Cyme. Spike. Raceme. Panicle. Corymb. Umbel. Cyme. 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 [Pg xii] [Pg xiii] [Pg xiv] VI. WINTER TWIG OF RED MULBERRY a. Tip-scar. b. Lateral bud. c. Leaf-scar. d. Stipule-scars. VII. WINTER TWIG OF BLACK WALNUT a. Terminal bud. b. Lateral bud. c. Leaf-scar. d. Bundle-scars. e. Pith. 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. 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. 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 [Pg xv] [Pg xvi] [Pg xvii] 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: a.Houses wood. b.Body paint brown. Smith’s house bb.Body paint white. c.Trimmings green color. Jones’ house cc.Trimmings slate color. Brown’s house aa.Houses brick. b.Roof gray slate. Johnson’s house bb.Roof red tile. Public Library 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: bb. c.Trimmings green color; gable roof. Jones’ house cc.Trimmings slate color; mansard roof. Brown’s house 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 [Pg xviii] [Pg xix] [Pg xx] 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 a.Leaves simple. b.Leaves needle-shaped, awl-shaped, strap-shaped or scale-like. c.Leaves in clusters of 2-many. d.Leaves in clusters of 2-5, sheathed, persistent for several years. PINUS, p. 4. dd.Leaves in fascicles of 8-many, on short, lateral branchlets, deciduous in autumn. LARIX, p. 17. cc.Leaves solitary, not clustered. d.Leaves opposite. e. Twigs flattened; leaves all of one kind, scale-like, decurrent on the stem; fruit a small, pale brown cone. THUJA, p. 31. ee. Twigs essentially terete; leaves of two kinds, either scale-like, or else awl-shaped, often both kinds on the same branch, not decurrent on the stem; fruit berry-like, bluish. JUNIPERUS, p. 33. dd.Leaves alternate or spirally-whorled. e.Leaves flattened, soft to the touch. f. Leaves 1/2-1-1/4 inches long, sessile, aromatic; cones 2-4 inches long; bark of trunk with raised blisters containing resin. ABIES, p. 27. ff. Leaves seldom over 1/2 inch long, short-petioled, not aromatic; cones about 3/4 inch long; bark of trunk without raised blisters. TSUGA, p. 29. ee.Leaves 4-sided, harsh to the touch. PICEA, p. 18. bb.Leaves broad and flat. c.Leaves alternate or clustered, never opposite nor whorled. d.Margin of leaves entire or only slightly undulate. e.Leaves heart-shaped or rounded; fruit a legume. CERCIS, p. 167. ee.Leaves oval, ovate or obovate; fruit not a legume. f.Branches armed with stout, straight spines; fruit large, orange-like. MACLURA, p. 133. ff.Branches without spines; fruit small, not orange-like. g.Fruit an acorn. QUERCUS, p. 96. gg.Fruit a drupe or berry. h. Twigs spicy-aromatic when bruised; leaves of many shapes on the same branch. SASSAFRAS, p. 139. hh.Twigs not spicy-aromatic; leaves not of many shapes on the same branch. i. Leaves thick, abruptly pointed, very lustrous above, not clustered at the ends of the branches. NYSSA, p. 209. ii. Leaves thin, long-pointed, not lustrous above, clustered at the ends of the branches. CORNUS, p. 202. dd.Margin of leaves serrate, toothed or lobed. e.Margin of leaves serrate to toothed. f.Branches armed with stiff, sharp thorns. CRATAEGUS, p. 151. ff.Branches not armed. g.Base of leaves decidedly oblique. h.Leaf-blades about as long as they are broad, heart-shaped. TILIA, p. 201. hh.Leaf-blades 1-1/2 - 2 times as long as they are broad, oval to ovate. i.Leaves thin, coarsely but singly serrate; fruit a globular drupe, ripe in autumn. CELTIS, p. 131. [Pg xxi] [Pg xxii] ii;Leaves thick, coarsely and doubly serrate; fruit a samara, ripe in spring. ULMUS, p. 122. gg.Base of leaves essentially symmetrical. h.Teeth coarse, 2-5 per inch of margin. i.Leaves very glabrous both sides; fruit a prickly bur. j. Leaves 3-5 inches long, very lustrous beneath; bark close, smooth, steel- gray. FAGUS, p. 93. jj.Leaves 6-8 inches long, not lustrous beneath; bark fissured, brownish. CASTANEA, p. 95. ii.Leaves pubescent or white-tomentose, at least beneath; fruit not a prickly bur. j. Leaves 2-4 inches long, broadly ovate to suborbicular; fruit a very small capsule, falling in spring. POPULUS, p. 44. jj. Leaves 4-7 inches long, oblong-lanceolate to obovate; fruit an acorn, falling in autumn. QUERCUS, p. 96. hh.Teeth fine, 6-many per inch of margin. i.Leaf-petioles laterally compressed; leaves tremulous. POPULUS, p. 44. ii.Leaf-petioles terete; leaves not tremulous. j.Leaf-blades at least 3 times as long as they are broad. k.Twigs brittle; fruit a very small capsule, falling in spring. SALIX, p. 34. kk.Twigs tough; fruit a fleshy drupe, falling in late summer or autumn. PRUNUS, p. 152. jj.Leaf-blades not more than twice as long as they are broad. k.Leaf-blades about twice as long as they are broad. l.Margin of leaves singly serrate; fruit fleshy. m. Lenticels conspicuous; pith whitish or brownish; bark easily peeled off in papery layers; buds ovoid. PRUNUS, p. 152. mm. Lenticels inconspicuous; pith greenish; bark not separable into papery layers; buds narrow-conical. AMELANCHIER, p. 149. ll.Margin of leaves doubly serrate; fruit not fleshy. m.Trunk fluted; fruit inclosed within a halberd-shaped involucre. CARPINUS, p. 83. mm.Trunk not fluted; fruit not inclosed within a halberd-shaped involucre. n. Bark of trunk gray-brown, broken into narrow, flattish pieces loose at the ends; fruit in hop-like strobiles. OSTRYA, p. 81. nn. Bark of trunk white, yellow or dark brown, platy or cleaving off in papery layers; fruit not in hop-like strobiles. BETULA, p. 84. kk.Leaf-blades almost as broad as they are long. l. Lower side of leaves more or less downy; sap milky; leaves not crowded on short, spur-like branchlets; fruit berry-like, black. MORUS, p. 135. ll. Lower side of leaves glabrous; sap not milky; leaves crowded on short, spur-like branchlets; fruit a large, green pome. PYRUS, p. 142. ee.Margin of leaves distinctly lobed. f.Fruit an acorn. QUERCUS, p.96. ff.Fruit not an acorn. g.Leaves fan-shaped, with many fine veins radiating from the base of the blade. GINKGO, p. 3. gg.Leaves not fan-shaped, without many fine veins radiating from the base of the blade. h.Leaf-lobes entire. i. Leaf-petioles 5-6 inches long; leaves lustrous above; twigs not aromatic when bruised. LIRIODENDRON, p. 137. ii. Leaf-petioles about 1 inch long; leaves dull above; twigs spicy-aromatic when bruised. SASSAFRAS, p. 139. hh.Leaf-lobes sinuate-toothed to serrate. i.Leaf-lobes coarsely sinuate-toothed. PLATANUS, p. 141. ii.Leaf-lobes serrate. j.Branches armed with stiff, sharp thorns; sap not milky. CRATAEGUS, p. 151. jj.Branches unarmed; sap milky. MORUS, p. 135. cc.Leaves opposite or whorled. d.Margin of leaves entire or only slightly undulate. e.Leaves 3-5 inches long; spray fine; fruit an ovoid, scarlet drupe. CORNUS, p. 202. ee.Leaves 5-12 inches long; spray coarse; fruit a long, slender-cylindrical capsule. CATALPA, p. 222. dd.Margin of leaves serrate to lobed. e.Margin of leaves finely serrate. VIBURNUM, p. 229. ee.Margin of leaves distinctly lobed. ACER, p. 172. aa.Leaves compound. b.Leaves alternate. c.Leaves simple-pinnate. d.Branchlets armed with short, sharp prickles. ROBINIA, p. 169. dd.Branchlets unarmed. e.Leaflets entire with the exception of 2 or more coarse, glandular teeth at the base. AILANTHUS, p. 171. ee.Leaflets serrate the entire length. f.Upper leaflets less than 1 inch broad. g.Trunk and large branches armed with stout spines; leaflets 3/4-1-1/2 inches long. GLEDITSIA, p. 165. gg.Trunk and large branches unarmed; leaflets 2-3 inches long. PYRUS, p. 142. [Pg xxiii] [Pg xxiv] [Pg xxv] ff.Upper leaflets 1-5 inches broad. g.Leaflets 5-11; pith homogeneous. CARYA, p. 66. gg.Leaflets 11-23; pith chambered. JUGLANS, p. 60. cc.Leaves bi-pinnate. d.Trunk and large branches armed with stout spines; leaflets 3/4 - 1-1/2 inches long. GLEDITSIA, p. 165. dd.Trunk and large branches unarmed; leaflets 2 - 2-1/2 inches long. GYMNOCLADUS, p. 163. bb.Leaves opposite. c.Leaves pinnately compound; fruit a samara. d.Leaflets 3-5; samaras paired. ACER, p. 172. dd.Leaflets 7-11, exceptionally 5; samaras not paired. FRAXINUS, p. 210. cc.Leaves digitately compound; fruit a prickly bur. AESCULUS, p. 194. WINTER KEY TO THE GENERAB a.Leaves persistent and green throughout the winter, needle-shaped, awl-shaped or scale-like. b.Leaves in clusters of 2-5, sheathed. PINUS, p. 5. bb.Leaves solitary, not clustered. c.Leaves opposite. d. Twigs flattened; leaves all of one kind, scale-like, decurrent on the stem; fruit a small, pale brown cone. THUJA, p. 31. dd. Twigs essentially terete; leaves of two kinds, either scale-like, or else awl-shaped, often both kinds on the same branch, not decurrent on the stem; fruit berry-like, bluish. JUNIPERUS, p. 33. cc.Leaves alternate or spirally-whorled. d.Leaves flattened, soft to the touch. e. Leaves 1/2 - 1-1/4 inches long, sessile, aromatic; cones 2-4 inches long; bark of trunk with raised blisters containing resin. ABIES, p. 27. ee. Leaves seldom over 1/2 inch long, short-petioled, not aromatic; cones about 3/4 inch long; bark of trunk without raised blisters. TSUGA, p. 29. dd.Leaves 4-sided, harsh to the touch. PICEA, p. 19. aa.Leaves not persistent and green throughout the winter, but deciduous in early autumn. b.Twigs, branches or trunks armed with stiff, sharp prickles, spines or thorns. c.Thorns or spines not exceeding 1/2 inch in length on the branches. d.Spines in pairs at each node; buds rusty-hairy, 3-4 superposed; fruit a flat pod. ROBINIA, p. 169. dd.Spines one at each node; buds glabrous, not superposed; fruit orange-like. MACLURA, p. 133. cc.Thorns or spines much exceeding 1/2 inch in length on the branches. d. Thorns usually branched, situated above the nodes; lateral buds superposed, the lower covered by bark; fruit a flat pod. GLEDITSIA, p. 165. dd. Thorns unbranched on twigs, situated at the nodes; lateral buds not superposed, not covered by bark; fruit a small pome. CRATAEGUS, p. 151. bb.Twigs, branches or trunks unarmed. c.Leaf-scars mainly crowded on short, stout, lateral shoots. d.Bundle-scar 1; fruit a cone, usually present. LARIX, p. 17. dd.Bundle-scars 2; fruit a globose drupe falling in autumn. GINKGO, p. 3. cc.Leaf-scars distributed along the lateral branches. d.Leaf-scars (or some of them) 3 at a node, i. e., whorled. CATALPA, p. 223. dd.Leaf-scars 1-2 at a node, i.e., not whorled. e.Leaf-scars 2 at a node, i.e., opposite. f.Terminal buds 1/2 - 1-1/2 inches long, resin-coated; twigs very stout. AESCULUS, p. 195. ff.Terminal buds rarely exceeding 1/2 inch in length, not resin-coated; twigs not conspicuously stout. g.Leaf buds with 1 pair of scales visible. h.Buds scurfy-pubescent. VIBURNUM, p. 229. hh.Buds glabrous. CORNUS, p. 203. gg.Leaf buds with 2 or more pairs of scales visible. h.Bundle-scars usually 3, distinct, separated. ACER, p. 174. hh.Bundle-scars many, minute, more or less confluent in a U-shaped line. FRAXINUS, p. 211. ee.Leaf-scars 1 at a node, i.e., alternate. f.Bundle-scars 1-3. g.Bundle-scar only 1, or appearing as 1. h. Twigs bright green, spicy-aromatic; bundle-scar appearing as a horizontal line; terminal bud present; pith homogeneous. SASSAFRAS, p. 139. hh. Twigs brownish, not spicy-aromatic; bundle-scar appearing as a large dot; terminal bud absent; pith chambered. CELTIS, p. 131. gg.Bundle-scars 3 or in 3 compound, but distinct groups. h.Terminal bud present. i.Stipule-scars present. [Pg xxvi] [Pg xxvii] [Pg xxviii] [Pg xxix] j. First scale of lateral bud directly in front, i.e., exactly above the center of the leaf-scar; twigs brittle; pith somewhat star-shaped in cross-section. POPULUS, p. 45. jj. First scale of lateral bud not directly in front, i. e., to one side of the center of the leaf-scar; twigs not brittle; pith circular in cross-section. PRUNUS, p. 153. ii.Stipule-scars absent. j.Buds bright to dark red, the terminal 1/8 - 1/4 inch long. k. Branches contorted, bearing many short, spur-like branchlets; fruit an apple an inch or more in diameter, light green. PYRUS, p. 143. kk. Branches not contorted, not bearing short, spur-like branchlets; fruit berry-like, 1/2 inch long, blue-black. NYSSA, p. 209. jj.Buds brownish to gray, the terminal exceeding 1/4 inch in length. k. Buds narrow-conical, sharp-pointed; leaf-scars small, narrowly crescent- shaped; twigs about 1/16 inch thick; pith homogeneous; fruit berry-like, not present. AMELANCHIER, p. 149. kk. Buds broadly conical to ovoid, blunt-pointed; leaf-scars conspicuous, broadly heart-shaped; twigs about 1/4 inch thick; pith chambered; fruit a nut, often present. JUGLANS, p. 61. hh.Terminal bud absent (sometimes present on short shoots of Betula). i.Stipule-scars present. j.Bud-scale only 1 visible; twigs brittle. SALIX, p. 34. jj.Bud-scales 2 or more; twigs not brittle. k.Bark smooth, close, warty or peeling into papery layers, but not flaky nor rough-ridged. l.Tip of bud appressed; fruit berry-like. CELTIS, p. 131. ll.Tip of bud not appressed; fruit not berry-like. m. Trunk fluted; catkins not present in winter; lenticels not elongated horizontally; low tree or bushy shrub. CARPINUS, p. 83. mm. Trunk not fluted; catkins usually present in winter; lenticels elongated horizontally; large trees. BETULA, p. 85. kk.Bark flaky or rough-ridged, not warty nor peeling off in papery layers. l. Bundle-scars depressed, conspicuous; bark thick, more or less deeply furrowed. ULMUS, p. 123. ll. Bundle-scars not depressed, inconspicuous; bark thin, broken into narrow, flattish strips, loose at the ends. OSTRYA, p. 81. ii.Stipule-scars absent. j. Buds silky-pubescent, depressed; twigs stout, clumsy, blunt, with conspicuous leaf-scars. GYMNOCLADUS, p. 163. jj.Buds glabrous, not depressed; twigs slender, with inconspicuous leaf-scars. k. Buds 1/8 inch long, obtuse, somewhat flattened and appressed; pith with reddish longitudinal streaks. CERCIS, p. 167. kk. Buds 1/8-1/4 inch long, acute, not flattened nor appressed; pith without reddish streaks. PRUNUS, p. 153. ff.Bundle-scars 4-many. g.Bundle-scars in a single U-shaped line. h.Terminal bud present; fruit berry-like; a shrub or small tree. PYRUS, p. 143. hh.Terminal bud absent; fruit not berry-like; large trees. i.Stipule-scars present; twigs slender. j. Stipule-scars encircling the twig; leaf-scars nearly surrounding the bud; bark peeling off in thin plates, exposing the lighter colored inner bark. PLATANUS, p. 141. jj. Stipule-scars not encircling the twig; leaf-scars not nearly surrounding the bud; bark thick, rough-ridged, not exposing the inner bark. ULMUS, p. 123. ii.Stipule-scars absent; twigs very stout. j.Bundle-scars usually not more than 5. GYMNOCLADUS, p. 163. jj.Bundle-scars usually 6-12. AILANTHUS, p. 171. gg.Bundle-scars variously grouped or scattered, but not in a single line. h.Terminal bud present. i.Stipule-scars present. j.Stipule-scars encircling the twig; visible bud-scales 2, united. LIRIODENDRON, p. 137. jj.Stipule-scars not encircling the twig; visible bud-scales more than 2, not united. k. Buds 4 times as long as broad, not clustered at the tips of vigorous shoots; fruit a prickly bur. FAGUS, p. 93. kk. Buds not 4 times as long as broad, usually clustered at the tips of vigorous shoots; fruit an acorn. QUERCUS, p. 98. ii.Stipule-scars absent. CARYA, p. 67. h.Terminal bud absent (occasionally present in Castanea). i.Bud at end of twig very obliquely unsymmetrical, mucilaginous when chewed. TILIA, p. 201. ii.Bud at end of twig symmetrical, not mucilaginous when chewed. j. Bud-scales 2-3 visible; pith star-shaped in cross-section; sap not milky; fruit a prickly bur, present; large tree. CASTANEA, p. 95. jj. Bud-scales 4-8 visible; pith not star-shaped in cross-section; sap milky; fruit berry-like, not present; small tree. MORUS, p. 135. [Pg xxx] [Pg xxxi] [Pg xxxii] MANUAL OF TREES DESCRIPTION OF SPECIES WITH SUMMER AND WINTER KEYS TO THE SPECIES GINKGOACEAE Ginkgo. Maidenhair Tree 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. [Pg 1] [Pg 2] [Pg 3] 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 a.Leaves 5 in a cluster; cones 4-10 inches long. P. strobus, p. 7. aa.Leaves 2 in a cluster; cones less than 4 inches long. b.Leaves 1-3 inches long. c. Leaves about 1 inch long, divergent; cones sessile, pointing forward towards the tip of the branch, persistent 10-15 years, opening very unevenly. P. banksiana, p. 9. cc. Leaves 1-1/2-3 inches long, slightly divergent; cones stout-stalked, pointing away from the tip of the branch, maturing in second season, opening evenly. P. sylvestris, p. 13. bb.Leaves 3-6 inches long. c. Bark of trunk red-brown; cones maturing in second season, about 2 inches long; cone- scales thickened at the apex, but unarmed. P. resinosa, p. 15. cc. Bark of trunk gray to nearly black; cones maturing in first season, 2-3 inches long; cone- scales thickened at the apex and topped with a short spine. P. laricio austriaca, p. 11. WINTER KEY TO THE SPECIES OF PINUS a.Leaves 5 in a cluster; cones 4-10 inches long. P. strobus, p. 7. aa.Leaves 2 in a cluster; cones less than 4 inches long. b.Leaves 1-3 inches long. c. Leaves about 1 inch long, divergent; cones sessile, pointing forward towards the tip of the branch, persistent 10-15 years, opening very unevenly. P. banksiana, p. 9. cc. Leaves 1-1/2-3 inches long, slightly divergent; cones stout-stalked, pointing away from the tip of the branch, maturing in second season, opening evenly. P. sylvestris, p. 13. bb.Leaves 3-6 inches long. c. Bark of trunk red-brown; cones maturing in second season, about 2 inches long; cone- scales thickened at the apex, but unarmed. P. resinosa, p. 15. cc. Bark of trunk gray to nearly black; cones maturing in first season, 2-3 inches long; cone- scales thickened at the apex and topped with a short spine. P. laricio austriaca, p. 11. White Pine [Pg 4] [Pg 5] [Pg 6]