Popular Science Monthly/Volume 22/November 1882/Some Curious Vegetable Growths
|SOME CURIOUS VEGETABLE GROWTHS.|
By W. H. LARRABEE.
THE importance of trees to the earth and to life does not need to be insisted upon. The condition of treeless regions is almost a demonstration that without them the soil would not be tillable and life would not be endurable. It is, therefore, natural that they should have at all times shared the special regards of men; and that not only-particular species, but individual trees, should in their times and places have been hallowed with a sacred, historical, legendary, romantic, or mythical interest. The list of such trees, if one should undertake to make it out, would fill a large catalogue. Our own country and time, commonplace as their characteristics are supposed to be, are not without them. Other trees have become famous by reason of their extraordinary size, or some other remarkable features of their growth; and in these points we are able to present specimens with respectable claims to honor. The big trees of California are equaled among the trees of modern, and, so far as is known, of ancient, periods only by a few Australian eucalyptuses. Many of the most remarkable specimens of vegetable growth are familiar by description; others are added to the list, from time to time, as new quarters of the earth are more thoroughly explored and their forests more closely examined, or seen with eyes keener in observation.
The forests of Europe still contain a few remarkable trees, the history of which has not become trite by familiarity. Mr. Gaston Tissandier's "La Nature" furnishes us with descriptions and illustrations of two noteworthy specimens of these growths.
Switzerland has its old chestnut-trees on the banks of Lake Leman, and the ancient linden of Fribourg, the history of which is said to go back to the time of the conflicts with Charles the Bold. M. Louis Pire, President of the Royal Botanical Society of Belgium, has found a fir-tree in the forest of Alliaz, Canton of Vaud, which he believes to be still older than the linden of Fribourg, and considers entitled to be regarded as the oldest and most remarkable tree in the canton, if not in the whole confederation. It is growing near the baths of Alliaz, at a height of about thirteen hundred feet above the hotel, and forty-five hundred feet above the sea, surrounded by a forest of firs, which it overtops by more than thirty feet. The trunk of this tree is ten metres, or a little more than thirty feet, in circumference at the base. At about a yard from the ground it puts out, on the south side, seven offshoots, which have grown into trunks as strong and vigorous as those of the other trees in the forest. Bent and gnarled at the bottom, these side-trunks soon straighten themselves up and rise perpendicularly and parallel to the main stem. This feature is not, perhaps, wholly unparalleled, but another most curious fact is that the two largest of the side-trunks are connected with the principal stem by sub-quadrangular braces resembling girders. These beams have probably been formed by an anastomosing of branches,
Fig. 1.—The Fir-tree of Alliaz. (From a sketch by Madame A. Pire.)
which, common enough among angiosperms, is extremely rare among conifers; but it has been impossible to ascertain the manner in which the ingrowing of one branch into the other has been effected. The adaptation by which a limb, originally destined to grow free and bear foliage, has been converted into a living stick of timber, is a strange one, and affords a new illustration of the power of nature to fit itself to circumstances. The space between the rough flooring formed by the growing together of the offshoots, at their point of departure, and the girder-limbs, is large enough to admit of building a comfortable hermit's hut within it.
Fig. 2.—Extraordinary growth of Pines in a Bohemian Forest.
Several forests are still existing in Europe in a primitive condition, some of the principal ones of which are situated on the vast estates of Prince Schwartzenberg, in Bohemia. In these forests are beech trees a hundred to a hundred and twenty feet high, with trunks three or four feet in diameter; and pyramidal pines, four to eight feet in diameter, and towering to a height of from one hundred and twenty to two hundred feet. The dense foliage of these gigantic plants excludes the rays of the sun, and keeps all around them in impenetrable obscurity. The voices of the birds are hushed, and the silence of the solitude is broken only by the soughing of the wind through the foliage of the colossal trees. Old trees, which have fallen and decayed, furnish a rich and congenial base in which young larches and pines readily take root, and from which they may grow for centuries, drawing nourishment from the juices supplied from the slowly rotting trunk. This, at least, appears to be the case with the trees in our cut, which represents an actual group of trees growing upon the trunk of a fallen ancestor, some of which are nearly as large as the decaying monster itself, while that still keeps its shape.
Herr Haeckel, in the "Letters of Indian Travel" which he is publishing in the "Deutsche Rundschau," gives some glowing descriptions of the beautiful and curious forms of tropical vegetation which he met in the forests and jungles and gardens of Ceylon. Down in the valley away below him, as he journeyed by rail from Kandy to Peradenia, he observed in the jungles which alternate with the cultivated lands, towering above all the other trees, the giant stems of the talipat palm (Corypha umbraculifera), "queen among the palms of Ceylon." Its perfectly straight white trunk resembles a slender marble pillar, and often rises to a height of more than a hundred feet. Each one of the fan-shaped leaves of its stately crown covers a semicircle sixteen feet in diameter, or a surface of two hundred square feet. Numerous applications are made of the leaves, the most important, perhaps, being for purposes of thatching. They formerly constituted the only substitute which the Singlalese had for paper, and are still used to a considerable extent for that purpose. The ancient puskola manuscripts in the Buddhist cloisters were all written with iron styles on ola-paper, or narrow strips of talipat-leaves prepared by steeping and drying them. The talipat blooms but once in its life, generally between its fiftieth and eightieth year. The magnificent pyramid of flowers rises from the top immediately above the mass of the foliage, to a height of thirty or forty feet, and is composed of millions of little whitish yellow blossoms; and the tree dies as soon as the nuts are ripe.
On the road between Colombo and Point de Galle, although the general character of the landscape varied but little, the traveler's eye was never tired, for the constant charm of the cocoa and the inexhaustible variety in the grouping of the palms prevented any monotony. The delicately feathered leaves of the cocoas, with the fanning of the sea-breezes, tempered the heat of the sun. without excluding his rays. The eye was constantly delighted with the endless variety of the clothing of the palm-stems with festoons of pepper-wort and other vines, swung like beautiful and artfully arranged garlands from tree-top to tree-top, and hanging down in bouquets of dense foliage set off with bright flowers. Under and among the stately palms were other trees, the noble mango and the large bread-fruit tree, with its thick, dark green crown of leaves. The slender, pillar-like stem of the handsome papaya-tree (Carica papaya) was elegantly inlaid and adorned with a regular diadem of broad, palmated leaves; and jasmin, orange, and lemon trees in varieties were covered over and over with fragrant white blossoms.
As the road neared the sea-shore, the pandanus, or screw-trees (Pandanus odoratissimus), picturesquely growing upon the rocky hills, attracted attention. These are among the most remarkable and characteristic plants of the tropics. They are nearly allied to the palms, and are often called screw-palms, or, improperly, screw-pines. The cylindrical stem of this plant, which seldom reaches more than from twenty to forty feet in height, is bent and twisted, and its branches are forked like a chandelier. Each limb bears on the end a dense tuft of large, sword-shaped leaves, like those of the dracæna and the yucca. The leaves are sometimes sea-green, sometimes dark-green, and are arranged spirally at the base, so that the limb resembles a regularly turned screw. At the bases of the leaf-tufts hang clusters of white, extremely fragrant blossoms, or large red fruits like the anana. The most remarkable feature of the plant is afforded by the numerous air roots which branch out from the trunk and ramify again, lower down, fastening themselves in the earth when they reach the ground, and forming buttresses to support the main stem. The tree looks as if it were walking on stilts.
The entrance to the Botanic Garden of Peradenia is through a noble avenue of India-rubber trees. This tree, which is known to us of the north only by puny specimens in greenhouses, grows in these tropical regions to a giant's stature, of a size comparable to that of our largest oaks. An immense crown of many thousand leaves covers with the aid of its horizontal limbs, which are thirty or forty feet long, the area of a stately palace; while from the base of its thick trunk extends a frame-work of roots over a space of often between one and two hundred feet in diameter, and much larger than would correspond with the height of the tree. This wonderful structure consists of twenty or thirty chief roots proceeding from as many corresponding ribs in the lower part of the trunk, and spreading themselves like great snakes on the ground. The tree is hence called the snake-tree by the natives, and has been compared by the poets to the coiled serpents of the Laocoön. The roots, with the ribs which mark their swelling out from the trunk, form strong buttresses to the tree, and enable it to bid defiance to the storm. The spaces between the buttresses constitute mimic chambers large enough for a standing man to conceal himself in them.
Among the other arboreal wonders of Peradenia are the giant bamboos, which are a marvel to all visitors. They here form thickets along the banks of the stream, a hundred feet high, and as many feet wide, bending their great heads, like the waving plume of a giant, high over the river and the adjoining road. On a nearer approach, each of the thickets is seen to consist of cylindrical stems a foot or two thick, which, closely crowded together below on a common root—offshoots from a creeping stem—diverge as they rise, and bear on slight, nodding branches dense tufts of the most delicate foliage. These gigantic trees are nothing but grasses. Like all grass-holms, their great hollow reed-stem is divided into joints; but the sheath of the leaf, which is represented in our tender grasses by a thin scale at the base of the leaves, becomes in these gigantic bamboos a hard, woody plate, that might without further preparation serve the purpose of an armor for the whole breast of a strong man. A three-year-old child could hide itself in one of the joints of the stem.
Not less interesting than the bamboos and the palms proper are the groups of thorny climbing palms, or rattans (calamus), with their fine waving feather-leaves. Their slender but hard and elastic stems, no thicker than one's finger, climb into the tops of the highest trees, and may reach a length of three or four hundred feet. They are the longest of all plants.
Herr Haeckel also speaks of the mangroves, whose branching roots form impenetrable thickets at the mouths of the large rivers; of the cactus-shaped wolf's-milk (Euphorbia antiquorum), with its naked blue-green prismatic limbs, near the rock-temple of Kaduwella; and of the Buddha-trees, Bogas, or sacred fig-trees (Ficus religiosa), generally found near the Buddhist temples, which with their venerable stems, fantastic roots, and colossal crowns of foliage, form a prominent feature in the picturesque surroundings of those buildings. "Their leaves, which are heart-shaped, with long stalks, quiver like our aspens." At one end of the town of Cultura, a magnificent banyan-tree (Ficus Indica) spans the road with its arch of roots. The gigantic trunk has thrown out air-roots which have grounded themselves on the opposite side of the road, and have grown up into large stems. These form now, together with the main stem, a high Gothic archway, to which picturesqueness is added by the ferns, orchids, and climbing vines that have grown upon the trunk. Near it is an India-rubber tree, whose buttressed roots, entwined together and rising in high lattices, form a labyrinth, in the sinuosities of which, when Haeckel visited the place, hosts of children were amusing themselves with playing at hide-and-seek.Australia possesses a diversified flora, consisting partly of forms peculiarly its own, partly of those allied to African and South American
Fig. 3.—The Monkey-bread Tree (Adansonia Gregorii) of Australia.
types. Its myrtles, proteazeas, acacias, and gum-trees exhibit most curious forms, and the grasses, ferns, beeches, araucarias, screw-palms, and bananas are represented; while the thorny rattans wind among the thickets so as to form impenetrable copses.
One of the most curious trees of Northwestern Australia is the monkey-bread tree (Adansonia Gregorii), a baobab, which is plainly distinguished from the African baobab (Adansonia digitata), the only species hitherto known, by its short fruit-stalks. The trunk is swollen to a considerable extent, and the tissues are charged with a mucus like that of the mallows, of which the sheep feeding in the region are very fond, and which they find quite refreshing. The tree is remarkable, among its fellow-plants of the sandstone table-land on which it grows, for its habit of shedding its leaves periodically—a peculiarity which is shared by hardly a dozen among all the Australian trees. Associated with this baobab are relatives of other African plants, of the leguminous Erythroplacum, or poison-tree, and the tamarind; and to these may be added an ally of the Indian crow-nut, or nux vomica.
Many of the Australian plants exhibit various aberrations in the form of their leaves, with some of which specimens of their eucalyptus have made us acquainted. The acacias, which are very abundant, and appear in three hundred species, are many of them, as well as some other leguminous plants, distinctly marked from similar plants in Asia, Africa, and America, by having not veined leaves but phyllods, or leaf -like structures, in which the petiole becomes so much developed as to assume the appearance and perform the functions of a leaf.Another remarkable adaptation of leaf-forms is exemplified in the Brazilian plant called the Bauhinia, the leaves of which are deeply cleft into two lobes, and given a form which is graphically described by the name Unha de boi, "ox-hoof," which the Portuguese give to the plant. At daybreak, the leaves are borne with both lobes spread out horizontally; as the sun rises in the sky, the lobes rise, and are drawn toward each other, till, in the more sensitive species (Bauhinia Braziliensis), they are completely doubled up, with their backs in contact. As the sun goes down, they begin to separate again, growing wider apart as the afternoon advances, till in the evening they appear again spread out level. During the night they again contract and become folded together. Herr Fritz Midler had an opportunity while in Brazil of observing one of these plants at noon, when a part of the leaves were shaded by the tree under which he was resting. Leaves that were quite closed together, or the lobes of which formed an acute angle with each other, spread out as soon as the shadow struck them, and eventually became horizontal, and even appeared to turn their lobes downward. In no other instance, however, did Herr Muller find the upper surface of the lobes of the leaves inclined to each other at a larger angle than 180.
Fig. 4.—Leaf of Bauhinia Braziliensis. a, folded; b, expanded.
An American prairie plant, commonly known as the rosin-weed or turpentine-plant (Silphium laciniatum), bas also been named the compass-plant, from the property its radical leaves have of pointing north and south. The phenomenon has long been known to hunters and frequenters of the prairies, and has been scientifically verified by General Benjamin Alford and other American and European observers since 1839. The secret of the property lies in the fact that the number of stomata is equal on both sides of the leaf, and both sides, therefore, are equally acted upon by light. Hence, if the leaf is equally exposed to the morning sun and the afternoon sun, it will naturally tend to assume a position of equilibrium between the two forces, by turning one side toward the morning, the other side toward the evening, sun. This would throw its breadth in a north-and-south direction. Since attention has been turned to this subject, the leaves of several other plants have been found to possess similar properties. Among them are some lactucas (or lettuces), the Chinese arbor vitæ, and a number of Australian plants. Whenever this peculiarity has been observed, it has also been found, on examination, that both sides of the leaves were structurally alike. The property can be brought out clearly under favorable conditions; but it is liable to be modified or marked, in the actual circumstances of growth, by any difference in exposure to the sun or wind, on different sides of the plant.