The romance of our trees

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Preface

IN THE following pages an effort is made to tell of the intimate association of trees and mankind from the earliest times. Simplicity combined with accuracy has been the aim, and technical language has been avoided. The opening chapters treat of trees in general and serve to illustrate the mutual dependence of the animal and vegetable kingdoms. The records of geology bear witness to the continuous and progressive change in character of the tree types, of the complete disappearance of many, and of the persistence of a few from Coalmeasure times down to the present. The protective influence of religion of many creeds is emphasized by the history of the Ginkgo and of the Cedar of Lebanon. The immense value of the Yew-tree to the warriors of the Middle Ages and influence of war-like migrations and wars of invasion in the distribution of fruit trees is told. As a corollary to the development of the civilizations of the Orient and Occident two parallel groups of fruit trees have x PREFACE

been developed, and the blending of these two groups by hybridizing may result in future fruits superior in quality to any we now enjoy. The romance, the more interesting folk-lore and mythology that have gathered round certain trees like the Apple and Yew give an insight into the early life of our forebears.

The types selected represent the patriarchs, the giants, the pygmies, and the curiosities of tree growth, and their importance in the embellishment of gardens, parks, and pleasure grounds is emphasized. The beauty of trees at all seasons, of their bark, their flowers, and their autumn foliage finds expression, and the cardinal idea permeating the whole work is to increase interest and love for trees and gardens. Trees are much more than sticks bearing leaves and useful as fuel and as a source of timber for construction purposes. They are, indeed, the most vigorous expression of life and its most enduring form this planet boasts, and a nation's trees should be esteemed as national treasures. A measure of a country's culture may be very accurately taken by an analysis of the position gardens hold in the people's esteem. In history books too much is told of man's destructive quarrels and too little about his constructive work in developing the arts of peace. Truly, if we delve into such mundane affairs as the development of

PREFACE xi

the fruits, the vegetables, the grains, and the common flowers of our gardens we may learn more concerning the real progressive development of the human race than is possible from the history books.

The preparation of these essays has been largely a recreation, and in sending them forth in collective form it is hoped that readers may find in the romance of our trees not only interest but inspiration. A resume of twelve chapters has appeared in The Garden Magazine for 1919-20; that on the autumn tints is reprinted from my "Aristocrats of the Garden." To the esteemed editor of The Garden Magazine I am indebted for helpful criticism; to the publishers, Messrs. Doubleday, Page&Co., my thanks are extended for the courteous manner in which they have met all suggestions.

E. H. Wilson.

Arnold Arboretum,

Harvard University.

Contents

PAGE

Preface ix

CHAPTER

Chapter I Their Ancient Lineage Chapter I Their Ancient Lineage

FROM the earliest glimpses preserved to us of the development of the human race we find that trees have exercised a beneficent influence on man's character and uplift. They figure prominently in the records, written and oral, of all religious systems in all parts of the world. Indeed, the connection of trees with religion is as old as the conception of the deity itself. North and south, east and west, we find the same idea. In the most universally prized of all the books, the Bible, trees are ofttimes mentioned. In Genesis, chap. II, v. 9, "And out of the ground made the Lord God to grow every tree that is pleasant to the sight, and good for food; the tree of life also in the midst of the garden, and the tree of knowledge of good and evil." All are familiar with the biblical story of man's fall and banishment from the Garden of Eden through disobeying God's commands in reference to these trees. 3

0. H. HILL LIBRARY North Carolina State College

Those who have studied the folk-lore of primitive man tell us that the legend of good and evil trees is almost universal, and that they are intimately connected with man's own story of his development. As man congregated, built homes of mud, brick, and stone, his energies became more and more absorbed in gaining wealth, and this has repeatedly led to his own destruction and that of his kindred. The same thing obtains to-day. The happy and contented among us are those whose thoughts are not wholly engrossed in laying up treasure in gold, silver, and precious stones but who take an intelligent interest in Nature's treasures, preserve them, and prize them at their true worth.

When looking at a tree — any tree — say in summer, what do we see? A stout stem or trunk firmly fixed in the earth and bearing aloft many branches, great and small, each more or less crowded with green leaves; occasionally flowers are conspicuous. Contemplating a wood or a forest we note the fact that trees are not all alike. They differ in size and form and in shades of colour, and, looking closer, we see that the stem may be white, gray, or nearly black, and that its surface may be smooth or rough; also that the outer covering of the stem may be loose and scale off in patches, thin or thick, in papery rolls, or, it may be firm and deeply fissured. In the autumn 4

THEIR ANCIENT LINEAGE

we note that on many trees the leaves change from green to beautiful hues of purple, crimson, orange, yellow, and leather-brown; in the winter that many trees are entirely leafless, look stark and dead, others bear brownish leaves which rustle in the wind but are obviously lifeless. Other trees, on the contrary, are clothed with small dark green or gray-green leaves even as they were in spring, summer, and autumn. Those of an inquiring turn of mind are quick to perceive other points of difference and soon realize that among the group of life-forms we designate as trees variety is infinite. Scarcely two are identical in outline and detail, and although some sort of classification is obviously possible, almost every tree has an individuality of its own. The beauty of trees — their form, foliage, flowers, and the tracery of their branches — appeals to the artistic instinct of man; their cool, shade-giving qualities in the heat of summer are appreciated by man and animals alike, and so also are the edible fruits which many kinds of trees produce in the autumn. But alas! the utilitarian spirit so dominates the world in general, and modern civilization in particular, that comparatively few people see anything in the trees which form our woods and forests except a source of fuel, of lumber, of pulp for papermaking or of some other product useful for manufacturing purposes. Too often even their very usefulness in the arts and crafts of man is ignored and

trees are regarded as mere useless encumbrances of

the ground to be ruthlessly felled to make room for

houses, fields, and highways.

Since our earliest days we have been familiar with

trees as things that are: what they are, and why they

are, interest but very few. A trip across the dreary

deserts and treeless plains of the western part of this

country brings many to an appreciation of trees and

green things generally. Would that more of us

could realize the truth so admirably expressed in the

splendid tribute to "Trees" by Joyce Kilmer who

was killed in the trenches of battle-scarred northern

France:

I think that I shall never see A poem as lovely as a tree; A tree whose hungry mouth is prest Against the earth's sweet-flowing breast; A tree that looks at God all day And lifts her leafy arms to pray; A tree that may in summer wear A nest of robins in her hair; Upon whose bosom snow has lain; Who intimately lives with rain.

Poems are made by fools like me, But only God can make a tree.

Rightly considered trees are the noblest product of the earth. Look how they rear themselves against gravity for from 50 to 100, aye to 400 feet; how 6

THE OLDEST LIVING THING IN THE WORLD

A TREE

GENERA1 SHERMAN BIG I KM IN SEQUOIA NA- TIONAL PARK, CALIFORNIA, 2,000 \l VRS OLD WHEN JESUS OF NAZARETH WAS BORN. II IS NOV 2~i) I I.

high; ;<>' ft. in diami 1 1 k {Sequoia sempervii

THE GREATEST MHMOKIAL AVENUE IN THE WORLD

PLANTED ALONG 24 MILES OF HIGHWAY AT NIKKO, JAPAN, LEADING TO THE TOMB OF IEYASU, FATHER OF THE SECOND SHOGUN OF THE TOKUGAWA DYNASTY. BEGUN IN l6>I AND COMPLETED IN 20 YEARS. THERE NOW STAND 18,308 TREES

(Cryptomeria japonica)

THEIR ANCIENT LINEAGE

they resist the storms of every season, the winter's cold, the summer's heat. They are a most wonderful expression of life, year by year adding to their dimensions — often through centuries — flourish whilst generations of mankind come and go, reach their optimum, produce seeds to perpetuate their kind, and finally obey the law inevitable: die, and give place to others. Their structure built of myriads of minute cells piled on and around each other and differentiated into tissues of varying thicknesses and forms as best adapted to the work each has to perform in the life economy of the whole organism.

The big roots firmly anchor the tree to the earth and give off tiny rootlets that absorb water and various food salts in solution which are carried upward through special tissues to the leaves. The leaves — the lungs and chemical laboratories of the tree — breathe in from the air during daylight a gas deleterious to man (carbon dioxide), break it up, exhale a part as pure oxygen essential for the life of the animal kingdom, and combine the remaining carbon and oxygen with the water and food salts supplied by the rootlets into simple forms of sugar, in which manner they are immediately available as food to nourish the tree's growth in all its complicated parts. So much of these sugars not at the moment wanted is converted into forms of starch and stored away for the tree's future needs. No chemical factory in the world built by man and fitted with all the wonderful appliances of modern science is half so marvellous as the leaf of any one kind of tree; no system of collection and transportation devised by human ingenuity and skill so perfect as that which serves each and every tree.

All who keep gold fish in a bowl or in an aquarium know that green weeds of some sort must be kept in the water or the fish will die. Why? Because the fish inhale all the free oxygen in the water and poison themselves with carbon dioxide, which they exhale unless plants are present to take up this gas and in exchange give back free oxygen and thus maintain the balance in nature. So on the grander scale. But for the presence of vegetation this earth would be unhabitable for the animal kingdom in all its forms, man included.

The two kingdoms — vegetable and animal — are interdependent, but the vegetable kingdom is the more ancient of the two. Men of great minds, both of the past and of the present, who have studied deeply the problems concerning the origin of the world of life are of the opinion that the present state of development of the animal kingdom — the living types of to-day including man the complex — has been made possible by the steady change in the 8

THEIR ANCIENT LINEAGE

development of the vegetable kingdom. The fossil remains of plants and animals imbedded in the rocks of the different geological epochs of the world's history tell the story of the progressive changes that have taken place during the earth's history, from its youth and adolescence to its present age. Indeed this progressive development of organic life through successive geological periods is the theory on which the modern teaching of the science of natural history is based, and it must be confessed that it goes far toward rendering intelligible natural phenomena as they exist to-day.

Trees by no means represent the oldest type of life-forms in the history of the vegetable kingdom; on the contrary, they are fairly modern. Geologists tell us that in the earliest phases of the world's history of which organic remains exist, the vegetable kingdom was represented by simple, aquatic, or semiaquatic plants, and the animal kingdom by sponges, worms, centipedes, and spiders. In succeeding ages land plants were developed. During the period represented by our coal measures (the Carboniferous period) and the lengthy epoch preceding it, the whole earth became more or less forest-clad with a low type of vegetation mostly allied to our Ferns, Horsetails, Lycopods, and ancestral forms of the Cycad and Ginkgo families.

This earliest luxuriant land vegetation — that which formed the great coal-fields of the earth — was probably adapted to the physical environment alone and was almost uninfluenced by the scanty animal life of the period. Reptiles and mammals were then differentiated, but the former, being better fitted to live upon the vegetation and to survive in the heavily carbonated atmosphere, increased more rapidly. This increase continued through the next two geological epochs and culminated in the next, the Jurassic period, which has been fitly termed the "Age of Reptiles." Rocks of this age are prevalent in the states of Wyoming, the Dakotas, Kansas, and Texas, and from them have been excavated, and sent to museums for preservation, remains more or less complete of the largest, the ugliest, and the most extraordinary forms of animal life the world has known.

The development of vegetation reacting on the climate and on the animal kingdom, and each on the other, induced constant change. In due course reptiles gave place to mammals, birds were differentiated and likewise insects in variety; Cycads, Araucarias, Ginkgos, Yews, Cedars, and other conifers came into being and, later, broadleaf and coniferous trees similar to those of to-day. It is not my purpose to trace this progressive change in further detail but the fact I do wish to emphasize is that isolated types 10

THEIR ANCIENT LINEAGE

of the archaic forms of trees have persisted down through remote ages to the present day. Of such may be instanced the Araucarias, now confined to South America and Australasia. A familiar example of these trees is the Norfolk Island Pine {Arancaria excelsa), so much in request for indoor decorative purposes in the colder parts of this country, and quite hardy in California. Other examples are the Cycads, which are found scattered through the Southern Hemisphere and northward to the Tropic of Cancer, the Cedars of Lebanon, of Cyprus, of the Atlas Mountains and of the western Himalayas; also the Ginkgo of China, Korea, and Japan.

Chapter II Their Present-day Distribution

CYPRESS OF MONTEZUMA

AT TULE, MEXICO, 1 6() FT. HIGH, I 46 GIRTH. ESTIMATED TO B E MUCH OLDER THAN 2,000 YEARS

{Taxodium mucronatum)

CHAPTER I I

THEIR PRESENT-DAY DISTRI BUTION

MANY persons take it for granted that the types of trees with which they are familiar are found all the world over; others more discerning know that every tree has birt a limited distribution covering at most a limited range of degrees of latitude and longitude. They know that the Oaks, Elms, Maples, Pines, and Firs are different on the east and west seaboards of this country; also that both differ from those of Europe on the one hand and of eastern Asia on the other. If one looks into the subject all sorts of curious facts are unearthed. For instance, the Tulip-tree and the Kentucky Coffee-tree are each represented by two species only, one of each in the eastern United States and another of each in central China. Of Douglas Firs, two species grow on the mountains of the Pacific Slope and two species in eastern Asia. The Honey-locusts grow in eastern North America, in eastern Asia, and in the Caucasus region. One species of Incense Cedar is 15 native of the mountains of California, another of the mountains of Formosa and southern China, while several species are indigenous to South America and New Zealand. Some groups of trees are represented by many species, others by one or two species. And so as study follows interest it is clearly seen that some groups are in the heyday of their youth, others in their prime, others on the wane — not as individuals but as groups. Reasoning on these facts the conclusion is naturally reached that in the progressive development of types of trees this is the natural sequence. It has been the same through the world's history. Types have arisen and disappeared, some completely, while others, altered and modified to meet the climatic and other changes, have persisted through very long periods of time, and are, as it were, living fossils.

With three of these ancient types of trees I shall deal at length in succeeding chapters, but, as an explanatory introduction, it is necessary to enter a little into the subject of plant distribution in general. A popular book is hardly the place for a full discussion of these matters, yet they are of such interest and importance that a few salient points cannot fail to be of use in understanding present phenomena of tree distribution. Savants have written much to explain particular cases, and as knowledge increases 16

PRESENT-DAY DISTRIBUTION

the whole question becomes more simple. The geological records, even of the Northern Hemisphere, are notoriously imperfect but as investigations proceed many links are forged and abysmal chasms bridged. The human mind, collectively or individually, will never achieve the infinite but it may learn enough to explain much intelligently.

If we are in the least degree to understand the present-day distribution of plants, and especially the isolation of groups of trees like for instance the Honey-locust (Gleditsia), and Sweet-gum (Liquidambar), which occur in Asia Minor, China, Japan, and eastern North America and each separated by thousands of miles of land and sea, it is necessary that we try and picture some of the changes time has wrought in the climate of the Northern Hemisphere. Geologists are pretty well agreed that the two great oceans, Atlantic and Pacific, have not changed much in the aeons of time since this earth began to cool. Seas, plains, mountain ranges, and large areas of land have, however, changed vastly though probably the depressions and elevations have maintained a fairly stable equilibrium — a sort of compensation balance.

The Tertiary period, that is the geological era immediately preceding the present, was one of great disturbances and the folding of the earth's crust, due to internal cooling and consequent contraction, made 17 vast changes in the earth's surface. Its close was marked by a period of great cold which wrought havoc among vegetation, and to-day much land that in Tertiary times was forested is hidden under enormous ice-fields. In Tertiary times most of the present Arctic Zone was probably free of ice, at any rate Spitzbergen, Greenland, Iceland, the extreme north of the mainland of America and Asia enjoyed a climate at least as mild as New England does to-day. Vast forests circled the whole of to-day's Arctic regions, for the land connection was complete. In those times the types of tree vegetation were similar throughout the whole Northern Hemisphere. Doubtless, then as now, species had a limited distribution, but the genera then, much more so than to-day, were widespread. Tulip-trees, Magnolias, Sweet-gums, Ginkgos, Sassafras, Sequoias, and, indeed, countless others grew in Europe, in America, and in Asia.

As the period of great cold came on so the vegetation was forced to migrate down the mountains and southward to escape destruction. As the ice crept southward so it destroyed the vegetation. The trees of Greenland, Spitzbergen, Iceland, of the regions separating North America and eastern Asia, were all destroyed. In this country they were forced south of Philadelphia (Lat. 400 N.) and where there was no continuous land connection they were oblit- 18

PRESENT-DAY DISTRIBUTION

era ted. In Europe they were swept almost to the very fringe of the Mediterranean and virtually all destroyed. In Europe to-day, only about three dozen genera of trees are found and even the species are very limited in number.

We are not concerned with the theories as to what particular astronomical change induced the Ice Age, but it is important to realize that the ice did not descend to equal latitudes all round the Northern Hemisphere. Japan and China escaped glaciation and, though the temperature must have been lowered, the vegetation suffered little harm. Of course there was a migration toward the south and a reverse one at the close of the glacial epoch. The net result is that the existing flora of the Chinese Empire and of central Japan southward, is really a miniature of the whole flora of the Northern Hemisphere in pre-glacial times. In China and in the parts of Japan indicated grow to-day many peculiar types, and all the principal genera of trees known from the other parts of the Northern Hemisphere except Robinia, Laburnum, Platanus, true Cedars (Cedrus), Sequoia and Taxodium; and of the latter two there are such very closely allied trees as Taiwania and Glyptostrobus. Fossils of many types which grow in the Orient to-day occur in Europe, and recent dredgings off the Dutch- English coast have added much to prove that the '9 ancient flora of Europe was similar to that now flourishing in the Far East. I do not mean that they were specifically identical but that the generic types were similar. If we picture to ourselves the onward, inevitable creeping southward of the ice we can easily understand how trees and other forms of vegetation were destroyed in its path, and only those which were able to reach places of sufficient warmth to maintain life survived. The greater the land extension toward the south the greater chances had the vegetation, and where the country was broken by mountain ranges advantageous regions were more easily found.

The ice on its path ground off the tops of mountains and scoured out valleys to a great depth, and when it retreated the face of much of the Northern Hemisphere was changed. It disappeared from sea-level valleys earlier than from mountain ranges and so isolated groups of vegetation. If we picture this, and remember that before the period of great cold set in the vegetation of the North was everywhere very similar, we can understand how to-day are found here and there groups of trees isolated by thousands of miles from their kindred. This explains the separation of the Cedars of Lebanon, of the Taurus, of Cyprus, of the Atlas Mountains and of the western Himalayas; also the isolation of the Nettle-trees, Honey-locusts, Sweet-gums, Walnuts, and others in the 20

PRESENT-DAY DISTRIBUTION

Caucasus region, in eastern North America and in the Orient. What were temperate regions in the north in Tertiary times are even now the frozen North, and the land of this region capable of growing forests is infinitely less than it was then. Deserts, seas, lakes, high plateaux, and mountain ranges influence climates, which strongly affect plant distribution. Birds, animals, air- and water-currents are all agencies in plant dispersal, and so to understand why this tree is here and not yonder involves the study of a number of cognate branches of natural history. Complex is the problem, but however little it is studied the marvels of the world we live in become more and more apparent.

Brief and fragmentary as this sketch is it would be more so did we omit mention of the influence of man. At what period in the world's history man first appeared is much disputed, but certain it is that, as soon as he became a sentient being, hunger caused him to investigate the vegetation and taught him to appreciate what was wholesome as food; providing himself with clothes, shelter, and weapons for protection followed. As he migrated so he carried with him plants that were of service to his needs, and, later, such as were a delight to his higher being. We know so little of the early peregrinations of the human race, or of where it had its cradle, that wecan say nothing of that remote and most interesting period. In the mythology, folk-lore, and sacred writings of all races of which we have knowledge frequent mention of trees is made. I nvading armies devastated countries and carried off useful plants, including fruit trees and the like, as spoils of war. Alexander the Great is but a name in history in spite of his great conquests, and of his work the only beneficial result to mankind remaining is the Orange-tree which his soldiers are said to have carried back from India to the shores of the Mediterranean.

Of the mighty migrations across Asia we know very little though it is certain that for centuries the great highways of commerce of the Old World were across central Asia. That the peach, orange, and certain of its relatives, were carried from China to Persia and that neighbourhood is certain, and that the walnut and grapevine were brought back is equally true. From the rich and famed China of old, plants useful and ornamental were also carried to Korea and Japan ; even as the apple, the pear, the cherry, wheat, and barley were carried here from Europe and later the peach, apricot, almond, date, vine, and the like. From this country the potato, tobacco, and maize were taken to Europe and to China. In later times ornamental trees, shrubs, and herbs have been carried far from their original homes.

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PRESENT-DAY DISTRIBUTION

In all this beneficent work man has been the organizing power, and could a thousand and one of the common plants around us tell their story it would fascinate the least attentive. This pen is indifferently equipped, but the purpose of this work is to show the intimate connection, the bond of companionship, as it were, between ourselves — mankind in general — and certain groups of plants. Animal life, in all its higher forms at any rate, is dependent for its very existence on the vegetable kingdom. Man draws much of his bodily sustenance from the products of plant life, and trees will yield, to all who heed their beauty and study them, mental enjoyment and healthful recreation.

n M Mill IIRDADV

CHAPTER I I I THEIR RUGGED TRUNKS

CHAPTER I I I THEIR RUGGED TRUNKS

MUCH of the beauty of any region is due to the trees which clothe the mountain slopes and river valleys or line roadsides and hedge-rows. This statement is commonplace, yet those who have crossed the treeless areas in this and other lands can best appreciate its full significance. In the summer time, when clothed with leafage, all deciduous trees may look very much alike to a casual observer. In the fall, when the change of colour in the leaves takes place, variety becomes apparent, but it is in the winter when the trees are naked that they best display their peculiar characteristics. A very brief study will enable any one in winter to pick out the Elm, Oak, Sugar Maple, Beech, Hickory, and Silver Birch. The general aspect, position of main branches, thickness of shoots, character of the bark, and often of the buds, each or several, afford easy clues to identity. Those who are born and live in the country readily recognize by intuition their neighbouring trees. Townsfolk have not the same opportunities

THE ROMANCE OF OUR TREES and must learn by study what countryfolk acquire through association.

Of the many attractive features of trees not the least is their bark, and in winter this feature is not only very pronounced but is often characteristic. The various organs of a tree, like those of the human body, have each their function, and that of the bark is protection. It protects the vital tissues, which lie near the periphery, from the heat of the sun's direct rays and from the intense cold of winter. We are not concerned with a scientific treatise on the origin of bark but a few simple facts are instructive since they enable us to understand how the various forms of the bark arise. When transplanting trees it is well known that care must be taken not to injure the bark, especially when it is smooth, and that in certain trees, the Holly for example, even moderate injury is fatal. In the Holly (Ilex), in Acer striatum, and other striped-barked Maples, and in a few other trees, the original cells of the outer surface keep pace by growth with the formation of new tissue in the interior. In this case no proper bark is formed, and any considerable injury to the skin, as it may be termed, of the trunk is fatal, since it cannot heal over. Such trees grow naturally in the shade of others and are thereby much protected. Most commonly, however, it is the layer of cells immediately within the 28

THEIR RUGGED TRUNKS

outer surface which becomes active and forms bark and continues to do so during the life of the individual. In some trees, like the Birch, as new layers are formed the older ones are partially or completely thrown off. In others, like the Beech, the growth is such that the bark firmly coheres and remains smooth on the outside. In the Oak, Elm, and Chestnut successive formations are amassed and the bark, though firmly coherent, becomes fissured and with age deeply and ruggedly so. In some trees the bark-forming cells, after a time, cease to function and fresh layers arise successively deeper and deeper within the tissues. When this happens, as in Sequoia, the bark is made up of different tissues and is known as fibrous. In most cases the bark is either thin and papery, firm and smooth, or fissured, but in some — Cork Oak, Cork Elm, and other trees — it is thick and corky.