Russel Wallace : Alfred Russell Wallace (sic)
of the Tropics (1867)
My object [It will be my aim & endeavour] in these lectures to give you a more [definite and a more] accurate notion of Tropical scenery and vegetation, and a more extended view of the various interesting problems connected with the organic life of the tropics, than can usually be found in books of travels. [I have myself had many years experience of tropical life, both in the Eastern and Western hemispheres, among the islands of the Malayan Archipelago and on the banks of the Amazon, the largest river of S. America and of the world.] It will be to the Malay Islands that I shall most frequently refer, for my illustrations of Tropical phenomena,--because,--having spent eight years in their exploration after leaving South America, it is to them that I most naturally turn in endeavouring to recall the various characteristic scenes of the Tropics. Our subject for this evening is, more particularly, the peculiarities of tropical vegetation.
Ideas of the Tropics. Those among you who have never approached the equator, have, no doubt, formed some picture in your own minds, of what the Tropics really are. You imagine, perhaps, a wonderful vegetation of Palms and tree ferns and broad-leaved hot-house plants, and gorgeous flowers, and festoons of creepers. You people these with chattering monkeys and screaming parrots, with gay butterflies and large glittering beetles. You think, in fact, of an amalgamation of all the hot-houses at Kew, with all the beasts and birds of the Zoological gardens, lit up by an ever-blazing sun, and thus form your idea of the tropics.
How far true. There are undoubtedly times and places, where such a luxuriant imaginary scene, will not surpass the reality; there are even bits of tropical scenery, of which you cannot possibly realize the grandeur and beauty, by any such combination of materials. But there are still more frequently occasions on which the reality will present you scarcely one of the items which go to form your imaginary picture, and yet there will still be a variety of constantly recurring phenomena, highly characteristic of the tropics.
General Phenomena of the Tropics. There is first the daily march of the sun, not rising obliquely as with us, but describing a semi-circle in the heavens; passing at noon nearly vertically overhead, and causing an absence of shadow for a short time, which is itself a striking phenomenon. There is the rapid transition for day to night and from night to day,--the new aspect of the starry heavens,--the uniform and intense heat,--the superabundant moisture,--the rapid growth of vegetation,--the omnipresence of animal life. These are all-pervading characteristics of the tropics, and are daily and hourly felt to be such, by the close observer of nature.
In considering a few of these peculiarities more in detail, it will be well to restrict our observations to the Equatorial region, or the belt of country 10° N. and S. of the equator, since it is here that all purely tropical phenomena are at their maximum, and can be most conveniently studied.
Heat of Tropics how caused. It is generally considered, that the great and uniform heat of the tropics, (on which all their chief peculiarities more or less depend)--is due to their position with regard to the sun, which is more nearly vertical than in the temperate zone. But this does not seem to account for all the facts, because the heat does not vary in proportion to the approach of the sun to the zenith.
For instance, in Java in the month of June, when the sun is in the Northern tropic, its altitude is from 60 to 58° at noon;--yet the hot season is then at its height, and the thermometer in the shade reaches daily from 92 to 96 degrees, and all animal matter putrifies in a few hours. At the same time in London, the sun is about 62° high at noon, and is above the horizon 16 hours instead of 12,--yet the temperature with us rarely rises above 80°,--the direct rays of the sun are seldom painful, and meat can with care be kept for some days. Besides this, the heat of the tropical sun is almost as great two, or even three hours before noon, when it is very low indeed in the sky. Exposure to it for a short time will blister the skin of a European as effectually as scalding water. It would seem, therefore, that the mere position of the sun, does not account for the heat of the tropics and its attendant effects; and we must look to some other causes of the phenomena, among which the most influential is probably moisture.
Moisture. An important characteristic of the equatorial regions and perhaps of the tropics generally, is the great amount of aqueous vapour in the atmosphere. During a great part of the year the air is nearly saturated with moisture, and owing to the high temperature, the quantity it can retain is very great. Even in the dry season when aridity seems to prevail and woodwork cracks and splits in every direction, the atmospheric moisture is still really much greater than in temperate regions, as is shown by the continued deliquescence of salt & sugar and the thick coat of rust formed on iron, during the slight nocturnal fall of temperature.
Effect of Aqueous vapour on Radiant Heat. Now Prof. Tyndall has shown, that aqueous vapour,--while transparent to direct sun-rays,--is almost impervious to the passage of radiant-heat or the heat given off by a warm body. The heated earth and all bodies upon it, cannot cool so fast, when surrounded by moist as by dry air. It follows, therefore, that even if the amount of solar rays falling on two given parts of the earth be the same, yet the sensible and effective heat produced, may be very different according as the surrounding atmosphere is moist or dry. In the one case the heat is absorbed more rapidly than it can be radiated, and therefore it accumulates;--in the other case it radiates or is lost more rapidly than it can be absorbed, and therefore the heat can never exceed a certain limit.
Illustrate by Diagram. Vessels of Water.
The Earth, therefore, is a reservoir of heat, which keeps up the temperature of the air in contact with it; and the quantity of heat in this reservoir will depend, not alone on the quantity that is poured into it, but also on the quantity that can escape from it. We can thus understand why it is, that although the sun at midsummer has the same altitude at noon in the island of Timor 10.° S. of the equator, and at Edinburg in Lat. 57.° N.,--with less than 12 hours sunshine in the former and nearly 18 hours sunshine in the latter,--yet in the one the heat of the air will daily rise to 90° or 95° while in the other it will be generally 70° or 75°. England and Prussia actually receive far more solar rays in the month of June than the island of Java, one of the most luxuriant tropical countries on the globe.
Condensation of vapour gives out heat. While I consider this to be the most efficient cause of the high temperature of tropical countries, at seasons when they receive such a comparatively small amount of solar rays, there are two others which tend to produce the same effect. One is, the abundant rains and dews of the tropics, the condensation of which from the atmosphere liberates a portion of heat. It is true the great evaporation during the day must tend to lower the temperature, but the balance is in their favour, since the whole of the surrounding oceans are evaporated to supply the vapour which is condensed upon their hills & forests, and thus, far more heat is given to them than is taken away.
Climate. The other circumstance in favour of tropical climate is, that the winds seldom blow directly north or south, but, owing to the rapid motion of the earth near the equator, always take an easterly or westerly direction, and thus, passing over warm countries, have little or no cooling effect. Warm winds Cold Polar Winds. In Europe on the contrary we have abundance of North & N. E. winds, which bring in a vast influx of cold air from the Polar regions, and effectually keep down the temperature of both earth and atmosphere.
Short Twilight. One of the striking phenomena of the tropics, and especially of the regions near the equator, is the shortness of the twilight, the rapid transition from day to night and from night to day. It is usual greatly to exaggerate this. Before leaving England I was told by a traveller, that if you were reading, and turned over a page as soon as the sun had set, by the time you had to turn the next page it would be too dark to see to read. I need hardly tell you the twilight is not quite so short as this would imply. As soon as the sun has set, a mellow light succeeds, which is almost a gloom by its contrast with the intensity of light as long as the sun is above the horizon. For about ten minutes there is no perceptible variation, but during the next ten minutes it gets rapidly dark, and at the end of half an hour it has deepened into almost complete night. Changes and signs at dawn. The same rapid changes occur in the morning. At about 1/4 past 5, no sign of day appears in the house, but strange cries of a few birds and animals will be heard, indicating that some faint signs of dawn appear in the East. The melancholy notes of the Goatsuckers may be heard at this time, strange croakings of frogs, the plaintive whistle of a mountain thrush or the barking note of the ground squirrel. At half past 5, or soon after, a glimmer of light penetrates through the windows, which, when once perceptible rapidly increases, till about 1/4 to six it is clear daylight. This scarcely changes in character till at 6, the appearance of the suns rim above the horizon, decks the dripping foliage with glittering gems, sends gleams of golden light far into the woods, and wakes up all nature to activity and joyousness. The birds chirp and flutter, parrots scream, monkeys chatter, bees hum about the flowers and gorgeous butterflies flutter lazily along, or sit with outstretched wings exposed to the warm and invigorating rays.
Beauty of Sunrise. The first hour of morning in the equatorial regions, possesses a charm and a beauty that can never be forgotten. All nature seems refreshed and strengthened by the coolness and moisture of the past night; new leaves and buds unfold almost before the eye, and young shoots of the bamboo and other plants may be observed to have grown many inches since the preceeding day. The temperature is the most delicious conceivable. The slight chill of dawn, which was itself agreeable, is succeeded by an invigorating warmth; and the bright sunshine lights up the glorious vegetation of the tropics, and realizes all that the magic art of the painter or the glowing words of the poet, have pictured as their ideals of a terrestrial paradise.
Vegetation. Undoubtedly these equatorial regions owe their chief beauty, to the variety and grandeur of their vegetation.
Forest Belt of Earth, at Equator. With but few and unimportant exceptions, a great forest band 1000 miles in width, girdles the earth at the equator. Where mountains rise above 6000 or 8000 feet their summits are often bare, though in many cases the forest rises to 10,000 feet. Sometimes this forest belt is wider, rarely narrower. Sometimes it descends farther south, or rises farther north of the equator, but it is always present, and is most fully and magnificently represented in the great valley of the Amazon in S. America, and over almost the whole extent of the Malay Archipelago in the E. hemisphere.
With but few exceptions (which I shall presently point out) the whole Archipelago from Sumatra to New Guinea and the Solomon Islands is one vast forest-clothed country.
I will endeavour to describe to you in some detail the aspect of these forests, because they are very much misunderstood.
Forests. A tropical forest does not always differ so much as might be expected, from one in this country. Sometimes palms and all purely tropical forms of undergrowth are absent, and then we perceive only an expanse of straight and lofty trunks, not very close together, and not often of very great size. The general effect is one of loftiness, solitude, and gloom. The trees seldom throw out branches at less than 50 or 60 feet high, but above that height, they spread into such thick intermingling canopies of foliage, as almost to exclude even the light of a vertical sun.
Borneo Forests. Let us now suppose that we are upon the N W. coast of Borneo, and that we ascend one of the rivers and explore the interior of the country. We see a flat swampy coast, everywhere margined with a low wall of light green vegetation, backed by a loftier line of forest. Here and there are abrupt isolated hills, rising like rocky, forest clad islands, out of a sea of verdure. Farther inland similar mountains appear, softened by distance to tender hues of blue and purple. The characteristic feature of the salt-water swamps, which we observe on entering a river, is the Nipa palm, which grows in clusters of huge pinnate leaves rising out of the mud or water and bearing large globular fruits like giant pine apples, close to the ground. These palms never have a trunk, but the stem grows rooting along the ground, often winding about like a great serpent. Along the sandy beaches the feathery Casuarinas grow abundantly. These are trees characteristic of Australia, and have perhaps spread along the shores of the Archipelago from that country. In the drier parts of the swamp grow many Pandani or Screw Pines, curious palm-like trees whose long stiff leaves grow in a regular spiral or screw. Some of these have a single erect stem, like a palm. Others are forked or branched. Some are weak, and trail their stems among trees & brushwood, and others are true climbers, twining around the lofty trunks of forest trees. They are almost as numerous and as varied as the palms of the higher country. Some of the largest, have huge sword-shaped leaves 15 feet long, and it is a strange sight to stand under one of these, and look up at this vegetable screw winding with mathematical regularity, around a thick palm-like stem. The leaves are used for making coverings of canoes and for sleeping mats. (Specimens)
When we pass beyond this swampy region, we come to a country which is generally level, but rather elevated, and sometimes uniformly covered with ridges and valleys of clay and gravel. Abrupt hills of porphyry, and others still more precipitous of limestone, rise here and there to the height of one or two thousand feet. On all these hills, as well as on the plain, are magnificent forests of timber trees, except where the ground has been cleared for cultivation, or where Dyak villages stand surrounded by groves of Areca palm and fruit trees.
Ferns. Everywhere in these forests, ferns are abundant. They grow upon the rocks and decaying trees,--they clothe the sides of ravines and the margins of streams. They climb up the smooth stems of the trees or form immense tufts upon the ground with fronds 8 or 10 feet long;--while occasionally the most elegant of the group,--the tree-ferns--bear their graceful crown of fronds on slender stems 20 or 30 feet high.
Specimens of Borneo Ferns.
Three groups of plants are more particularly conspicuous in the lofty virgin forests and on the mountains, clothing the trunks and branches of trees with a singular and beautiful vegetation. These are the Bromelias the Arums and the Orchids. Bromelias. The first, are plants something like the pine-apple in general appearance, but often much larger and less rigid, & sometimes with broader and sometimes with narrower grayish foliage. Almost every large tree supports some of these, and those that have large horizontal branches hanging over a river or over the sea beach, are frequently crowded with hundreds of these plants.
Arums. The Arums are either epiphytes or climbers, and offer a great contrast to the last group, having broad, arrow-shaped, glossy, dark-green leaves, often curiously lobed or incised, and sometimes reticulated with large open spaces, as if pieces had been eaten out of them by voracious insects. They send out aerial roots by which they are enabled to cling to the smooth trunks of the trees, sometimes in great clumps, sometimes winding and climbing up them, so as to constitute a most characteristic feature in all the damper and more luxuriant forests.
Orchids. The third group, the Orchids, are equally abundant with the last, but much more varied. They grow on the stems, in the forks or on the branches of trees, abounding on fallen trunks, spreading over rocks and precipices, and occasionally, like our northern species, growing on the ground among grass and herbage. In most places where there is any variety of aspect,--as on a mountain-side,--a good collector would find 100 species of orchids,--some so small and insignificant as to look almost like mosses, others sending out masses of leafy stems 10 feet long (Grammatophyllum). Yet you must not suppose that the whole forest is like a huge orchid house, glowing with colour and fragrant with delicious odours, for it is only occasionally that a species is found in flower, and even then a very large proportion are obscure and inconspicuous.
Vanda lowii. One of the most remarkable is the Vanda Lowii, which grows on the lower branches of trees, and drops down its pendant flower-stalks to the length of eight feet, resembling a slender cord along which are strung at short intervals, large, star-like, crimson spotted flowers.
Another group of plants of great beauty are the Zingiberaceæ (? Scitamineæ) or Ginger-worts. These grow upon the ground, sending up long stems clothed with broad lily-like leaves, and often bearing oval spikes of rich yellow or crimson flowers. In swampy places and on the banks of streams, we often come upon complete thickets of these plants, which, when in flower are exceedingly beautiful; and they are so often met with as to form an important item in the general effect produced by tropical vegetation. Insert here "Pitcher Plant." [1/3 of Lecture]
[[inserted pages]] Perhaps the most curious of all vegetable forms is the Nepenthes or Pitcher plant, which is found abundantly in the Westn. half of the Archipelago while it is almost unknown in the Eastn. half. These plants grow in swampy places, but chiefly on the mountains. Some of the mountain tops and rocky ridges in Malacca and Borneo are covered with them, and their curious and beautiful pitchers may be seen in every stage of growth. The water they contain is often a great assistance to travellers, and though rather dirty & full of insects, is very palatable. Some of the finest species known were found on the summit of Kinabalu, the highest mountain in Borneo, by Mr. Low. (Figs. In Linn. Trans. Vol. 22. 18__)
These plants form a distinct natural order and are not closely allied to any other group. The structure of the pitcher is so complicated & extraordinary being developed upon the elongated midrib of the leaf, that it appears to me to offer one of the greatest puzzles the naturalist has to solve, and upon which, even the theory of Nat. Select. throws as yet no light.
The limited distribution, however, of this form of plants, and their great isolation in the system, would seem to indicate, that they are but a small remnant of a once extensive group, which flourished at some former period of the earth's history under conditions perhaps very different from those that now prevail. Perhaps an examination of the fossil flora preserved in the tertiary coal measures of Borneo, may furnish some clue to the early history and affinities of these remarkable plants. [[end of inserted pages]]
Palms. Although palms are the most characteristic and striking among the varied forms of vegetable life we meet with in the tropics, they are by no means universally present. Large tracts of forest may be passed through without ever seeing one, except where native huts or plantations exist, for then there are sure to be some species cultivated. In Borneo the Areca or betel-nut palm, a graceful species of moderate size which produces the favourite stimulant of the natives, is the most universal. In the forests the most abundant forms, are the Caryotas with huge curving leaves bearing triangular toothed leaflets; and the little fan-leaved Licualas whose leaflets appear as if they had all been cut off at the end. But a host of others are found, each in its favorite locality,--little slender palms that seem only adapted to make walking-sticks, and tall stemmed giants whose trunks would serve for the columns of a Grecian temple.
Calamus. In the drier parts of the forest the genus Calamus, the Canes or Rattans of commerce, are often abundant, and are characteristic of the Eastern forests. Rattans. There are more than 60 Malayan species, varying from the thickness of a quill up to that of the wrist, and almost every kind has some peculiar properties known to the natives, which renders it fit only for particular kinds of work. Some are brittle others are tough. Some will do only for house work, others will stand the weather. Some are best for making chairs others for twisting into cables. These prickly, climbing, rope-like, palms, present a remarkable appearance where they are abundant, and sometimes render the forest almost impassable. They lie about the ground, coiled and twisted, and looped, in the most fantastic manner. They hang in festoons from trees and branches. They stretch up suddenly to the tops of trees like the rigging of ships, or coil loosely among shrubs & in thickets, like endless serpents. When followed out in all their convolutions, they sometimes reach 600 or even 1000 feet in length, and are probably the longest of known vegetables. The cause of this extraordinary development is not at first apparent, but it is easily explained. Rattan Forests. By means of its prickly stem and hooked leaves, the calamus mounts to the top of the nearest tree, and by exposure to the bright sun-light and free air, produces its flowers and fruit. This would be in ordinary cases the limit of its growth. But should its supporting tree fall to the ground, either from its own decay or crushed by the fall of some neighbouring patriarch of the forest,--it has again to seek warmth & light, and starts into renewed activity. It works it way among the tangled mass of branches till it comes in contact with another tree by which it can mount again to the summit of the forest. Again and again, in the course of a century, this may take place, and each time the tangled coils of the cane become more complicated. Each tree that has carried it down in its fall, in turn decays,--first the branches and then the trunk, till at last scarcely a fragment of them is left, and there is nothing to mark the place where they were, but the strange coils of the living cane, remaining as a puzzle to those, who have not worked out the problem of its existence.
Bamboo. There is one other vegetable production which plays such an important part in the life of the Eastern tropics, that it must not be too hastily passed by. I refer to the Bamboos,--a group of gigantic grasses, which are found more or less plentifully in all the hot regions of the earth, but are especially abundant in the East in dry and mountainous situations. The stem of the bamboo varies in size from the thickness of a quill to that of a man's thigh, and from 10 to a hundred feet in height. A fine clump of large bamboos, is the most graceful of all vegetable forms, resembling more than any thing else the light and trembling plumes of the bird of paradise, copied on a gigantic scale in living foliage. Bamboos are often planted near houses and villages, on account of their usefullness. Their beauty is never thought of by the natives, although to the traveller from the temperate zone they form one of the greatest charms of a tropical landscape. There are a great variety of species of these plants,--differing in size and proportions,--in the comparative length of the joints, in the thickness and strength of the tube,--in their straightness, smoothness, hardness, & durability. There are probably a hundred different sorts in the Malay islands, almost all of which have special uses. The bamboo is wonderfully well adapted to the uses of half civilized man, in a wild country; and the purposes to which it is applied are almost endless. It is a natural column or cylinder, very straight, and uniform in thickness, of a compact and solid texture and with a hard smooth flinty external skin. It is divided by ringed joints at regular intervals, which, correspond to septa or partitions within, so that each joint forms a perfectly closed water-tight vessel. Owing to its hollowness, it is wonderfully light compared with its strength. It can be chosen of almost any size and proportions, and can be cut or split with the greatest ease, so that in a few minutes it can be fashioned to uses which would require hours or days of labour if solid wood had to be used.
I will just mention a few of the uses to which I have myself observed it to be applied in the Malay Islands, and every traveller in other parts of the tropics could add greatly to their number.
Spear. Easily made -- cutting edge. (See Fig.)
Bow. Split bamboo. String of Bamboo bark.
Spud. For planting & weeding
Yoke for carrying loads -- Bow reversed.
C. Utensils. -- Hat, made in Bali 10d. plain 5d.
10. Baskets -- skin of bamboo instead of wicker, open.
Mats -- skin of bamboo plaited close
Floor Mats -- small Bamboos, crushed & plaited (Fig.)
Umbrella made in China
9. Blinds -- screens. Parallel strips. fastened with rattan.
7. Flooring. open. Large bamboo split twice, tied down.
8. Floorings slabs. Very large bamboo, nicked at joints, split on one side & opened flat, 3-4 ft. long.
13. Entire houses at Lombok.
11. Rafters -- ready made.
1. Ladders (see 1a) -- very easily made, notch above joint for step holes.
2. Steps on ground up steep hill. (Fig.)
3. Masts for small Praus, yards & sprits.
4. Outriggers -- very buoyant.
5. Rafts of immense bundles of bamboo, floating houses along river at Palembang, anchored, rise & fall with the tide.
Cordage. Small species, flexible, thick as quill.
6. Bridges, to pass precipices, & hanging Bridges over rivers in Borneo.
14. Water vessels. Generally used, not breakable, easy to carry. Thin bamboos 4 ft. - 5 ft. long easy to pour.
15. Water pipes, aqueducts. Split bamboos.
16. Measures, Drinking Cups, -- Dippers. (Fig.)
17. Tobacco Boxes, -- Tinder Boxes. (Specimen.)
18. Bird Perches with food boxes &c Single piece. (Fig.)
Bird cages -- Plaited, or strips stuck through Sago pith.
19. Musical instruments. (Harp, Timor) Strips (Java.)
12. Chairs & Sofas, Bedsteads. good chairs, light strong and handsome at Ternate 5d. each, arm chair 10d. Sofa 2s. Bedstead 4s.
1.a Climb trees, pegs & ladders for Bees Wax in Borneo, dead orang-utan,-- bare trunk, 100 feet high.
20. Paper from Bamboo leaves, China
21. Bamboo shoots, -- an excellent vegetable equal to artichokes.
To all these various uses, the Bamboo can be adapted with the least possible labour, and is thus the greatest boon which nature gives to the wild inhabitants of the Tropics.
Scarcity of Flowers. You will be no doubt wondering, that all this time I have said scarcely anything about the flowers of the tropical forests. You will have probably expected some mention of those magnificent plants you see at our flower-shows and in our hot-houses, and which you are accustomed to think of as abounding everywhere in the tropics.
I am compelled however to tell you, that this is quite a mistake. As a general rule there are no flowers, in the forests. As a general rule, the most luxuriant equatorial scenery is devoid of brilliant colour. Now and then an exception occurs. Occasionally you meet with a shrub or tree, one mass of crimson or yellow, of pink or violet-blue. Occasionally you come upon some space on the banks of a stream, or on the margin of an old clearing,--festooned with flowering creepers and gay with blossoms. But you must never forget that these scenes are exceptions. You may pass weeks without seeing a strikingly beautiful flower;--you may wander for 100 miles and see nothing but the varied greens of the forest foliage, [Half--at the Middle] and the deep gloom of its sunless recesses. Such masses of gay colour, as our fields of buttercups, our gorse-clad commons,--our woods carpeted with the wild hyacinth, and our hill-sides glowing with the purple heather,--are unknown in the luxuriant tropical forests. So far as the effects of colour produced by vegetation, are concerned, the temperate is far superior to the torrid zone, whatever may have been said or written to the contrary. And, if ever, near the equator, a wide spread abundance of flowers is met with, it is sure to be in some locality where the distinctive features of tropical luxuriance are absent. On some lofty mountain, or in some sandy waste,--where vegetation seems to have lost half its vigour,--we most frequently meet with flowers in such plenty as to give a distinctive feature to the landscape.
And the reason of this is obvious. In the forest, all trees & shrubs & creepers struggle upwards to the light, there to expand their blossoms and ripen their fruit. Hence the abundance of climbers, which make use of their more sturdy companions to reach this necessary of vegetable life. Flowers. The flowers of the great forests, are therefore, chiefly far over-head; but even here there is not the gay scene that may be imagined, for a very large proportion of the tropical trees have flowers as small and inconspicuous as our own oaks and elms and ashes;--and those that do produce bright-coloured blossoms, seldom occur in numbers together, and seldom remain in flower more than a few weeks in the year. It is therefore often the case, that, when from some elevated point you can gaze over a wide expanse of unbroken forest, not a single bright-coloured object can be discerned. At other times, when more trees are in flower, you may behold scattered at wide intervals over the mottled green expanse, a few masses of yellow, white, pink, or more rarely of blue, indicating the position of handsome flowering trees. There are also a few trees, which flower in the depth of the forest shades, and these often produce a finer and more striking effect than any others. I once saw in the forests of Borneo, a number of small erect trees whose stems [Anonaceæ.] appeared as if closely wreathed with garlands of vivid crimson flowers, forming one of the most strangely beautiful scenes I have ever witnessed. (See Fig. in large view.)
Flowers. A partial exception to the scarcity of flowers occurs in cultivated districts, such as the vicinity of old settled towns, for there are abundance of showy tropical plants, that spread as weeds over open waste grounds, and there are others which when once cultivated grow almost wild, so that on the road-sides and in old gardens amid palms and fruit trees, a number of showy flowers are often to be seen. It is from such situations, that locomotive travellers often derive their chief impressions of a tropical vegetation.
Forest. But, although the charm lent by an abundance of gay & brilliant flowers, is generally wanting in the virgin forests of the tropics, they yet possess an interest and a grandeur, altogether peculiar to them. Forest trees. The wonderful variety of large trees,--their strange modes of growth, their straight and lofty trunks, the dense mass of foliage high over head, the weird gloom and solemn silence, combine to produce a sense of the vast,--the primæval,--almost of the infinite. It is a world in which man seems an intruder, and where he feels overwhelmed by the vastness of the forces, which, from the simple elements of the atmosphere, are ever building the vast mass of vegetation which overshadows the earth. The universal upward struggle towards the light, produces a straightness and regularity in most of the trees that is very imposing. They rise like columns of various sizes, and often to the height of 60 or 80 feet without sending out a branch. Yet amid this general uniformity there is a wonderful variety of aspect. The trunks vary much in colour and appearance;--some are nearly white,--others green, brown, or nearly black;--some are perfectly smooth, others deeply cracked and furrowed,--while in others the bark splits off in flakes or hangs down in long ribbands.
The most striking differences, are however, in the mode of growth of the stem. Some rise straight out of the ground like a doric column from its basement,--others are enlarged at the bottom like most of our own trees. In some this enlargement is so extraordinary as to form what are termed buttressed trees, which are quite a feature in most tropical forests. Large thin slabs, radiate from the main trunk to a considerable distance, standing up against it like the buttresses of a gothic cathedral. These often divide, and sometimes twist and curve along the ground for a considerable distance, forming elevated roots, so that when one of these trees is cut down near the ground it presents a strange appearance (Fig.). The trees that have this character, belong either to the Bombaceæ (the Silk Cotton tribe), or to the Leguminosæ, and are allied to the Locust tree. They seem to grow rapidly, and to reach an immense size without a proportionate development of roots. The buttresses, therefore, give them an extended base, and enable them more securely to maintain in an erect position the enormous weight of their spreading crowns, when swayed to and fro by a tempest. These buttresses are very useful to the natives, when light and soft planks are wanted, as for paddles or stools. By hacking out a square piece he at once obtains a board, sometimes quite flat and of a nearly uniform thickness of 2 or 3 inches.
Furrowed Trees. Another curious form of tree, is one on which the trunk is deeply furrowed and indented, often so much so that it appears as if made up of a number of poles or creepers which have grown together towards the centre. I saw one of these trees cut down, and took accurate sections of the stem, which shew its extraordinary character better than any description. It was a noble forest tree 200 feet high, but slender in proportion. (See Fig.) There are other examples of this, or a similar tree, in which the junction of the component parts is so imperfect, that large gaps or holes are left, by which you can often see completely through the trunk in several places, which appears so remarkable that it is only by repeated and careful examination that the observer is convinced it is not produced by decay or accident. Trees formed from Climbers. There are, in New Zealand, trees whose mode of growth has been traced, and which perhaps throw light upon these curious forms. A climber roots itself in the fork of a large tree, and sends down aerial roots which clasp the stem and lead to the death of the tree. The climber then increases rapidly, sends out large and massive branches, and by the time its original support has decayed away, it has formed a straight solid trunk and a large crown of branches, and has changed from a small creeper to a noble forest tree,--occupying the exact spot where its foster parent once stood. I think it probable that some of these curious furrowed and perforated trees may have arisen in a similar manner.
Fig Trees. Still more extraordinary and majestic are the various species of the fig tribe of which the Banyan of India is a well known example. They are very various, but their general character is to have a stem formed of an immense agglomeration of stems and aerial roots, rising to a great height and bearing an immense spreading crown of dark green foliage. Some of these trees are among the most striking and wonderful of the productions of the tropical forests. They are great favorites with the natives, who preserve them if possible near their houses and villages, where they often form very imposing objects. From the great amount of shade they afford they are great places of resort, and there is generally a market of fruits and palm wine held under them. They are especially interesting also to the naturalist, since they often bear a great variety of parasitic plants, and their fruit is exceedingly attractive to birds. When the fruit is ripe these great fig trees swarm with birds morning and evening. Great harsh-screaming hornbills, booming pigeons & cooing doves, as well as immense variety of small birds, flock to them at day break, and make it easy for the traveller to procure at once a variety of specimens and a good dinner.
Aerial Roots. There is yet another group of trees in the forest that always struck me as being still more fantastic and inexplicable than any of those I have yet mentioned. These are large and lofty trees, which yet have nothing that can be called a trunk, since they are all roots and branches. The roots seem to be entirely above ground, and present the most extraordinary complication of woody rigging crossed and entangled in every direction. These roots rise 70 or 80 feet above the ground, to where the stem ought to be, but at this point the tree begins to branch out into a spreading crown of foliage. It is possible to get in among these roots and stand in the very centre exactly under the point of junction of the roots and branches. (See Fig.)
This specimen was observed in New Guinea, but similar ones are occasionally found in most of the islands. It was situated in a dense and gloomy forest and so surrounded by trees and shrubs that I came upon it quite unexpectedly, and was greatly struck by the singularity and solitary grandeur of the scene, which I often again visited.
I was always puzzled how or why such a tree grew in this manner, and can only explain it on the supposition that it began life as a parasitical climber, and that the point where it first took root in the fork of some pre-existing tree, is now the place whence the aerial roots and branches diverge.
Java Mountains. In the fertile and well-cultivated island of Java, there are a number of volcanic cones which are more than 10,000 feet high, and many of them are clothed with forest to their summits. In ascending one of these mountains, many fine types of vegetation may be studied to advantage. At an elevation of about 4000 feet the tree ferns are very abundant, almost filling some of the deep ravines, and when seen from a favourable point, where you can look down over an expanse of their radiating crowns, and up at their delicately cut fronds sharply defined against the sky, the effect is one which can never be forgotten, and to which there is nothing else in nature at all comparable.
On these mountains, ferns of every kind are very abundant. Every tree and every rock is clothed with them, and new forms constantly meet the eye. I was told by a Dutch resident Botanist, that 300 species had been collected on the single mountain I ascended. Orchids are also very abundant, but comparatively few have showy flowers. Mr. Lobb, who had been long collecting in Java, informed me, that he estimated there were 500 species of Orchids in Java, but that not more than half a dozen or a dozen were handsome enough to be commercially valuable. Mountain vegetation of Java. The most interesting feature to the naturalist who has been long resident in the tropical plains, is, the appearance of temperate forms of plants upon these mountains. Even at 3000 feet, in the cultivated grounds, little violets and strawberries, combined with the pleasant coolness of the atmosphere remind one of Europe. Up to 5000 feet however the forests exhibit all the luxuriance and majestic beauty of tropical vegetation. The trees are of gigantic size, and the large-leaved wild Bananas, and Scitamineæ with brilliant flowers, as well as tree-ferns, abound. On the ground and among the rocks the beautiful and varied foliage of Melastomas and Begonias are particularly abundant and pleasing to the eye, while between them, and on every trunk and stump, ferns, mosses lycopodiums and orchids, spread and intermingle in endless variety. When we pass 5000 feet, Equiseti or horsetails resembling our European species, appear; and above 6000 feet mountain raspberries of three sp. abound on the road-side. At 7000 feet, Cypresses appear, and the other forest trees get much dwarfed in size; and after 8000 feet there is an abundant undergrowth of Lonicera Hypericum & Viburnum, all very characteristic of the N. Temperate zone. On the summit of the mountain, which is an undulating hollow plain (the extinct crater) there are great bushes of Artemisia & Gnaphalium, white and yellow Cruciferæ, sowthistles, chickweed & ranunculus. On the skirts of the slope and under the shade of the thickets, are honeysuckles and St. John's wort, while in the dampest shades grows the Imperial cowslip the most beautiful plant of the genus, and which is found only on this one mountain top in all Java or in the world.
The occurrence of N. Temperate forms of plants on the summits of isolated mountains in a tropical island S. of the equator, is a fact of the greatest interest, and suggests a problem of much difficulty. Something similar occurs in N. America, where on the summits of the White Mountains in New Hampshire U. S., arctic species, and many even identical with those of the European Alps, are found, while all around their bases, a flora of a peculiarly American character covers the country. This has been satisfactorily explained as one of the effects of the glacial period, the reality of which has been proved by much independent evidence. During that epoch, arctic plants alone could have existed in N. temperate America & Europe. When a warmer climate returned, they gradually retreated to the arctic regions, but those that grew on the lower slopes of mountains retreated more readily up the mountains, to the colder regions immediately above them, and now remain on their summits, a striking evidence to us of those changed conditions which have separated them so widely from their ancient associates. The same general principles have been applied by Mr. Darwin to explain the occurrence of European genera of plants on tropical mountains. He supposes that there have been one or more earlier glacial periods of greater intensity, when a much lower temperature than at present, prevailed, even on the equator. As a warmer period came slowly on, those plants which were not adapted to support heat, crept gradually northwards, or up the slopes of the adjacent mountains, by which they obtained a similar decrease of temperature.
Mountains of Java. In the case of Java, it is evident that temperate plants could only have entered in any quantities if it had been formerly connected with the continent of Asia, and of this there is independent evidence, in the great shallowness of the intervening seas, and in the identity of many of the large animals of Java with those of the adjacent parts of the continent. Into this subject I cannot now enter, but it seems clear that it is only by some such hypothesis as this, that we can account for the presence of these familiar plants on mountain summits, separated from their nearest allies by thousands of miles of a widely different vegetation.
The general aspect of the forests of Celebes, the Moluccas and New Guinea, does not differ very materially from what has been already described, but the surface of the country in those islands being more abruptly varied with hill and dale, ravine and precipice, the forms of vegetable life show themselves to greater advantage, and the scenery is generally more picturesque. In New Guinea, palms are very abundant, and in this respect as in some others the forests of that country bear a considerable resemblance to those of the distant valley of the Amazon.
Timor Group--distinct vegetation. The only portion of the Archipelago which produces a vegetation widely different from the rest, is the chain of islands East of Java as far as Timor. These are all volcanic except Timor itself which consists of various slaty and coralline rocks which have been geologically speaking recently elevated. The situation of these islands exposes them to the full influence of the S. E. winds, which blowing over the dry and heated plains of Australia for seven or eight months in the year, gives them an unusually arid climate. Their porous, volcanic or coralline, & much fractured rocks, tends to increase this aridity, and the only vegetation they can support is of a peculiarly stunted rigid and spiny character. In the thickets and low woods which cover these islands, spines thorns and prickly hooks meet one everywhere, and render it almost impossible to penetrate them. Abundance of Accacias and Eucalypts give the plains and mountain slopes of Timor quite an Australian aspect, and in that large island there is not a single tract of luxuriant forest like that which almost entirely covers the rest of the Archipelago. The Sandal-Wood tree abounds here, and its fragrant yellow wood is one of the chief exports. It is used in China to burn in temples and at private altars, and both there and in India is manufactured into many ornamental articles.
Tropical fruits. Among the popular delusions on the subject of tropical forests, it is supposed, that they not only abound with splendid flowers, but furnish also a constant supply of delicious fruits. Nothing can be farther from the truth, and any are compelled to trust to them would be very likely to die of hunger, or to make himself seriously ill by the nasty indigestible things he would have to feed on. It is a remarkable fact, that all the fine fruits of the East,--the Mango, the Mangustan, the Durian, the Jack fruit, the Lansat, Pine apple, Banana and others,--are just as much cultivated fruits, as pears, peaches, and plums are with us;--and their wild representatives, when they can be found, are seldom more eatable than our crabs and sloes. It is really a fact, that there are more eatable wild fruits in England than in most tropical forests. Our nuts and blackberries are really good, and are very abundant;--whereas in the tropics any wild fruit at all eatable is a rarity.
Sago Palm. There are however many plants that supply good and wholesome vegetables, and a native lost in the forests would not starve for want of food. One of the most extraordinary productions of the Malay Archipelago in this respect, is the Sago palm, a short account of which will perhaps interest you. This tree grows in swamps in Borneo, the Moluccas and N Guinea. It is a palm with rather a thick stem, and very large prickly pinnate leaves. It is one of those trees that only flower once, after having attained maturity at about 10 or 15 years growth. Just before this period the tree is cut down to make Sago. The whole trunk, perhaps 20 feet long and 4 ft round, is a mass of yellowish-white pith, penetrated by strong woody fibres at regular distances of about 1/4 inch. The first process is to clear a few feet of ground around the fallen tree, and then to cut a broad strip of bark off the upper side exposing the pith. To extract this a heavy club is used, having a piece of quartz fixed in the thick end. A blow with this, cuts away a narrow strip of pith which falls in a kind of coarse powder, and this is regularly repeated till the whole is cut away, and the trunk left as a thin hollow cylinder. The pith is now carried to the nearest water, and, with an apparatus entirely constructed of the leaves of the tree itself, it is washed and the flour or starch extracted. (Describe Diagram.)
Sago bread. The wet starchy mass is packed in cylindrical baskets made of sago leaves. It is either boiled into a thick and very sticky pudding and eaten with salt and chili peppers,--or baked into cakes which when fresh are soft and agreeable, but when dried in the sun become as hard as stone and will keep for years. In this state they are carried all over the Eastern half of the Archipelago, where they furnish the food (Specm. of Cake) of the more civilized, and the luxury of the savage tribes. A good sized Sago tree will yield 600 lbs. of dried cakes (1800 in number,) and as four or five of these are as much as a man can eat in a day, the tree will keep him for a year. The labour required to make this quantity, is about 10 days work; and if a man possesses sago trees of his own, with this amount of labour he can live for a year. But most of these trees are private property and a tree costs about 8s. There is probably no where in the world where a years bread can be obtained with so little foresight and labour, and the natural consequence is, that nowhere are the natives so idle, poor, and wretched, as in the sago countries.
But, besides producing food, the Sago palm is useful in a variety of ways. The stalks or midribs of the leaves are 12 or 15 feet long and thicker than a man's arm, and are almost a light and strong in proportion as a gigantic quill, being composed of a fine compact pith covered with a thin hard skin. These, pegged together side by side and fastened to timbers top & bottom, form entire houses. They are also used for roofing poles and even for flooring. When carefully split and shaped smooth, they are formed into light boards, and combined into boxes, for clothes and other purposes, and are one of the established manufactures of Ceram where Sago is very abundant. The leaflets folded across the smaller midribs and tied side by side, form a durable roofing thatch which is universally used. (Ceram Box.)
Sugar Palm. Another tree of considerable importance to the Malays is the Arenga saccharifera or Sugar Palm. (See Fig.) This tree is extensively cultivated, and also abounds in a wild state. The sheathing bases of the leaf stalks give out at their edges a quantity of strong black fibres like very coarse horse-hair, from which cheap and useful ropes are made very serviceable for native vessels. But this palm is chiefly remarkable for the immense quantity of sugary sap secreted at the flowering season, and obtained by cutting off the flower stalk as soon as the blossoms open. Several quarts or even gallons of juice a day are then poured out for some weeks, and where the trees are abundant this forms the chief drink of the natives. When fresh it is a sweet brisk refreshing liquor, but in a few hours it ferments and becomes palm wine or toddy. Some bark of a bitter and astringent quality is then [[rinsed ?]] and steeped in it, and this checks the fermentation and enables the wine to be kept some days. When this is done at an early stage, the toddy is very nice resembling new sweetish table beer.
New source of Sugar. When the fresh juice is boiled, it yields good sugar of a dark brown colour but very agreeable taste. Great quantities of this are manufactured in small cakes, formed by pouring the hot syrup into cocoa-nut shells, and is much esteemed as a luxury by the Malay sailors. Sugar palm. It has been lately pointed out by Mr. De Vry, a Dutch chemist who studied the subject in Java, that great advantages would accrue from the cultivation of this tree in place of the sugar cane. According to his experiments, it would produce an equal quantity of sugar of good quality, with far less labour and expense. The most striking advantage however would be, that no manure or cultivation would be required, and the land would nevertheless not be impoverished, as it so rapidly is, by the growth of sugar cane. The reason is this. The whole produce of a cane field has to be carried off the ground, and the various salts & minerals which form part of the woody fibre and foliage, become exhausted in the soil and have to be supplied by the application of manures. In the other case, nothing is taken away but the juice itself. The foliage as it decays falls upon the ground & becomes incorporated with the soil, and thus a plantation of these palms may be kept up perpetually on the same spot, because the sugar and water which are all that are taken away, are derived entirely from the atmosphere in which all their elements abound. Another thing to be considered is, that these trees will grow on the poorest rocky soil, and on the steep slopes of ravines, where other cultivation is impossible. The labour required to attend to them, is of that light and intermittent kind exactly suited to races to whom severe long continued labour is not congenial. These combined advantages appear to be so great, that it is to be hoped the experiment may soon be tried in some of our tropical colonies.
Characteristics of the Forest. In this necessarily imperfect sketch of the vegetation of the TROPICS and especially of the Malay Archipelago, I have endeavoured to dwell chiefly on the main features, and to call your attention to what is really characteristic of tropical scenery. The virgin forest of the tropics is grand and overwhelming by its vastness, and by the display of a force and vigour which the vegetation of [[ ? ? ? ]] displays. Among its best distinguishing features are, the variety of forms and species which everywhere meet and grow side by side,--and the extent to which parasites, Epiphytes, & creepers spread new modes of life into every available situation. If the traveller notices a particular tree and wishes to find more like it, he may often turn his eyes in every direction in vain. Trees of varied forms, dimensions, and colours, are everywhere around him, but he rarely sees any one of them repeated. Time after time he goes towards a tree which at a distance looks like the one he seeks, but a closer examination proves it to be distinct. He may at length perhaps meet with a second specimen half a mile off, or may fail altogether till on another occasion he stumbles on one by accident.
This absence of the gregarious or social habit, so general in the forests of extra-tropical countries, is probably dependent on the equability of the climate. Atmospheric conditions are much more important to the growth of plants than terrestrial ones. The severest struggle for existence plants have to undergo, is that against climate. As we go further and further north, the variety of groups and species regularly diminishes,--more and more are found unable to sustain the severities of winter.--Near the Polar circle, only two or three species of trees can exist, and the same is the case towards the limits of perpetual snow on high mountains. The extreme northern forests are of birch or of pine only,--slight differences of climate aspect or soil, causing one or the other to succomb in the struggle for life. In the tropics, and especially near the equator, there is no such struggle against climate. Its general and steady heat & ample moisture is adapted for all forms alike, and thus none can gain the advantage or monopolise territory to the exclusion of the rest.
Again, hardly a tree exists but what supports many other forms of vegetation, and some are so crowded with them that their forks and horizontal limbs are a very garden. Creeping ferns run like ivy up the smooth trunks, an immense variety of climbers hang in tangled masses from the branches or mount over the highest tree tops: Orchids bromelias Arums & ferns grow from every boss and crevice and cover the fallen and decaying trunks with a graceful drapery. Even these parasites have their own parasitical growth, their leaves often supporting abundance of minute creeping mosses and jungermanniæ. The forests of immense antiquity--Result of endless modifications.
[[the following section is crossed out]] Such a forest as I have attempted to describe to you, may be looked upon as a type of a high and complicated civilization,--in which a superabundant life and vigour everywhere reigns,--in which the variety of conditions and modes of existence is very great, and in which every sphere of action is appropriately filled. Just as the great trees of the forest all rise up to a pretty uniform level,--so in a highly civilized society, a large proportion of its members will be nearly equal, in education, tastes, & feelings;--although they may differ widely in fortune appearance or abilities, even as the forest trees differ in bulk, in symmetry and in the quality of their timber. The numerous creepers and climbers, which sometimes shoot up even above the tops of the loftiest trees,--may well represent that large class of men, who, with very slender means or abilities of their own, rise only by their connection with the great or wise; and, unscrupulously making use of their advantages sometimes elevate themselves for a time above the level of their supporters;--while the immense numbers and variety of the smaller plants and shrubs and epiphytes, which live under the shade, or are supported on the trunks and branches of the larger trees,--illustrate that dependence of classes, and variety of conditions, which, as far as we are able to see, must ever prevail. [[end of crossed out section]]
To the student of Nature the vegetation of the tropics will ever be of surpassing interest, from the variety of forms and structures it presents, and the vigour and luxuriance with which the life of plants there displays itself; while it can hardly help suggesting new ideas as to the laws which have governed the production and development of such infinitely varied forms.--When for the first time the traveller wanders in these primæval forests, he can scarcely fail to experience sensations of awe, akin to those excited by the tempest-tossed ocean, and the raging hurricane.
There is a vastness, a solemnity, a gloom,--a sense of solitude and of human insignificance, which for some time overwhelms him; and it is only when the novelty of these feelings has passed away, that he is able to devote himself to the examination of, the interesting, varied, and beautiful forms of life,--of which their dark recesses yield an inexhaustible harvest.
Copyright: Alfred Russel Wallace Literary Estate.