Popular Science Monthly/Volume 82/January 1913/Some Impressions of the Flora of Guiana and Trinidad
|SOME IMPRESSIONS OF THE FLORA OF GUIANA AND TRINIDAD|
By Professor HOUGHTON CAMPBELL
TO most botanists in America a visit to the tropics is supposed to be a difficult and expensive undertaking, involving much special preparation and also a good many risks. The fact is, a trip to the West Indies is a very simple matter, and even a few weeks are sufficient to give one an excellent idea of the main features of a most interesting and characteristic tropical flora, and is no more expensive than a journey of equal duration in Europe. If one extends the trip to include the Isthmus of Panama and Trinidad, one sees to great advantage the rich and beautiful flora characteristic of equatorial South America, one of the most individual floral regions of the world.
There are various ways of reaching the West Indies and northern South America, especially since the great development of the fruit industry, which employs many vessels plying constantly between the different ports of the Atlantic and Gulf States, and various ports of the West Indies and Central America. In addition, the Royal Mail (English), and the Dutch Royal Mail have steamers plying between New York and Europe via the West Indies and South America.
It may be mentioned, also, that a trip to the tropics in summer is not at all the trying experience that many persons suppose. Of course, it is hot, and in most parts of the West Indies rainy in summer; but the heat never equals that sometimes experienced along our own Atlantic coast, and, moreover, there are none of the sudden changes that are so trying. The same clothing that is suitable for hot weather in New York will be found quite appropriate for the tropics.
With the great improvements in sanitation of late years there is very little danger from the fevers which formerly gave this region such a bad name. With ordinary precautions, there need be little apprehension on this score.
Having a few weeks at his disposal, the writer decided to go to Europe via the West Indies, instead of by the shorter, but infinitely less interesting, route across the northern Atlantic.
Wishing to see something of the South American mainland, it was decided to go first to Paramaribo, the capital of Surinam (Dutch Guiana), as it is possible to go there directly from New York, in about ten days. From Paramaribo it is two or three days to Trinidad, where one can catch the Royal Mail for England.
The route from New York to the Guianas lies to the eastward of the larger West Indian Islands—the Greater Antilles—and passes close to the line of smaller islands, the Lesser Antilles. These are for the most part extremely mountainous, and the larger ones, like Dominica and Martinique, are exceedingly beautiful, and are also said to be most interesting botanically. Dominica, especially, with mountains rising some 5,000 feet above the sea, and evidently presenting great variety of conditions, made one wish that the ship would stop long enough to enable one to explore the luxuriant forest clothing the steep mountains to their summits.
Passing close to Martinique the sinister bulk of Mt. Pelée dominated the view, and the ruins of St. Pierre could be plainly seen—now after ten years largely overgrown by the rank tropical vegetation which is rapidly covering up the evidences of the great catastrophe.
No stop was made until Barbados was reached. This densely populated island is mainly devoted to the cultivation of sugar, and there is very little forest left. Moreover, unlike most of the West Indian islands, the elevations are comparatively slight, and the conditions much more uniform than in the other islands. To a newcomer in the tropics, however, no doubt the many striking cultivated plants will be a novelty. Some of the showiest flowering trees and shrubs, like the gorgeous flamboyant Poinciana regia and the beautiful frangipani (Plumiera), come to special perfection in the gardens of Barbados. Here one sees also the very striking mixture of races found in the West Indies—negroes form a large majority of the population, but there are many East Indian coolies; and a considerable number of Chinese. The white population is insignificant compared with the various colored races.
The next stop was made at Georgetown, the capital of British Guiana, or Demerara. The ship remained all day in port, and there was an opportunity to go on shore and visit the pretty botanical gardens. The town itself is attractively laid out, and the gardens full of luxuriant tropical growths testify to the thoroughly tropical climate. Fine avenues of tall palms are a striking feature of the town. These were apparently mostly the royal palm (Oreodoxa regia), but it is not always easy to distinguish this from the even finer cabbage palm (O. oleracea).
The botanical garden is really an attractive park rather than a scientifically laid out botanical garden. It contains, however, many fine specimens of palms and other tropical plants which will interest the botanist. Perhaps the finest features of the garden are the extensive lily ponds, where one can see growing with wonderful luxuriance the Victoria regia and other tropical water lilies. A pond full of lotus (Nelumbo) with thousands of white, pink and crimson flowers, was a truly magnificent sight.
Unfortunately, practically none of the original forest has been left in the immediate vicinity of the city, and one must go a long way before one can see the untouched native vegetation.
A day's sail from Demerara brings the traveler to Paramaribo, the capital of Surinam (Dutch Guiana). Paramaribo is a picturesque town, the high-gabled houses with their quaint stoops and doorways looking curiously alien under the shade of great mahogany trees and royal palms. Some of the houses, the former residences of wealthy Dutch merchants, are fine examples of their kind, and recall the flourishing days of the seventeenth and eighteenth centuries when the trade of Surinam was much more important than it is to-day.
The streets are lined with rows of palms and other tropical trees, among which the finest are the gigantic old mahogany trees.
The botanical gardens lie on the edge of the town, and are devoted principally to the cultivation of various economic plants—cocoa, rubber of various kinds, oranges, mangoes, bananas, coffee—and other less known tropical products.
To the botanist, undoubtedly the most interesting feature of the garden is a tract of untouched forest immediately adjoining it. This is an excellent sample of the predominant forest of the region. The greater part of this forest is more or less submerged for much of the time, but at intervals in this swamp are low ridges of more sandy soil, and in these drier areas grow the largest trees, two of which, the silk-cotton (Ceiba pentandra) and the sand-box (Hura crepitans) are veritable giants. The trunks and branches of these great trees were covered with numerous epiphytes, among which the Bromeliaceæ take first place. Several species of Tillandsia, including the familiar T. usneoides, the "Spanish moss" of our own Gulf States, were conspicuous. Clinging to the giant trunks, or festooned from tree to tree, were many lianas, some of great size. Convolvulaceæ, Bignoniaceæ, and especially the giant scandent Aroids—Philodendron, Monstera, Syngonium, and others—were noticeable among the tangle of creepers.
An undergrowth of dwarf palms and many showy Scitamineæ, especially species of Canna and Heliconia, gave the finishing touch to this truly tropical picture.
Almost no ferns were to be seen, and bryophytes—especially liverworts—were few and inconspicuous. Of the latter, only a few small leafy Jungermanniaceæ, growing on the tree trunks, were noted. In the town, and about the garden, a few epiphytic ferns were common.
These included species of Polypodium and Vittaria. This poverty of the fern flora is quite in accord with the account given by Spruce of the forests of the lower Amazon.
Through the kindness of Dr. Cramer, the director of agriculture, and other members of the scientific staff, an opportunity was afforded of visiting a number of the most characteristic regions within reach of Paramaribo, and an excellent idea was thus obtained of the more salient features of the flora of this region. Excursions were made up the Surinam River and some of its tributaries, as well as to one of the characteristic "savannas" occasionally met with in lower Surinam.
Except in the immediate vicinity of Paramaribo there are no roads, and communication (except for one line of railway) is almost entirely by means of boats, which ply along the rivers, creeks and canals with which the whole country is intersected.
Owing to the flatness of the country, the tide extends for a long way up the larger streams, and these rivers are everywhere bordered by an impenetrable mangrove swamp, in the lower reaches of the rivers composed almost exclusively of Rhizophora mangle, but higher up, where the salinity of the water is less, the Ehizophora is gradually replaced by Avicennia nitida, which sometimes becomes a large tree, whose aerial roots often develop from the upper branches and reach an enormous length. Back of the mangrove belt there sometimes occur slightly elevated ridges upon which the largest trees grow.
Nearly all of the cultivated land in lower Surinam has been reclaimed by building dykes, and the old sluice gates, two or three hundred years old, in some cases, are a characteristic feature in the landscape.
Two of the large plantations were visited, and an opportunity was thus given of seeing the methods in use in the cultivation of the various tropical productions of Surinam—cocoa, coffee, oranges, bananas, cassava, rubber, etc. On one estate there were extensive plantations of Para rubber (Hevea braziliensis), and the somewhat primitive, but apparently satisfactory, preparation of the sheets of merchantable rubber could be seen in all stages.
In these large plantations the canals intersecting them in various directions were the principal means of communication, although along the dykes were usually footpaths, which were not always, however, in the best of condition—especially when the clay was slippery after one of the frequently recurring showers.
As the salinity of the water decreases in the upper reaches of the rivers, the mangrove formation is gradually replaced by other trees and shrubs. Several Leguminosæ, especially species of Inga, are common, and great numbers of a big Arum (Montrichardia arborescens),
a constant feature of the brackish and fresh-water swamps, form dense thickets, the crowded bare stems forming a close palisade fringing the margins of the rivers. With the decrease in the salinity of the water, also, palms of various kinds begin to appear, and these constitute quite the most striking growths of the forest along the fresh-water streams. They occur in immense numbers and great variety, and some of them are extremely beautiful. First in abundance—and perhaps also in beauty—is Euterpe oleracea, whose slender stems and graceful crowns of feathery leaves occur by thousands. Other conspicuous palms are species of Attalea, Maximiliana, Astrocaryum, Manicaria, and others. Several small palms, especially species of Bactris, occur in great numbers as an undergrowth in these swampy forests. Another striking palm is a Desmoncos, whose flexible thorny stems and graceful pinnate leaves, armed with savage hooked thorns, were festooned from tree to tree. This palm closely resembles the rattan palms of the old world. Its large clusters of scarlet berries were conspicuous, and often attracted attention as the boat skirted the dense mass of vegetation along the shore.
In addition to the many native palms, a number of exotic species are cultivated. Among these are the African oil-palm (Elæis guinensis), the royal palm and the cocoanut. The last, however, does not thrive, due perhaps to the excessive moisture in the soil.
A very common and wide-spread member of the tropical American flora is the genus Cecropia, whose slender branches and big palmate leaves occur everywhere.
As might be expected, the development of climbing plants is extremely luxuriant in these wet forests, and in many cases the lower trees and bushes were almost smothered by the dense curtain of creepers of various kinds with which they were draped. These creepers belong to very diverse families—Convolvulaceæ, Passifloraceæ, Apocynaceæ, Melastomaceæ, etc., and many of them have flowers of extraordinary beauty, which add much to the attractiveness of these rich forests.
Very different from the wet forests are the "savannas," one of which was visited. These savannas are in many respects like the moorlands of more northern regions. The soil of the one visited was a coarse sand covered with a sparse growth of coarse grasses and sedges, with scattered clumps of low shrubs, among which were growing a number of orchids. Only one of these, a Catasetum with large greenish flowers, was found in bloom. There were here and there shallow pools, in which were growing tiny yellow Utrieularias and minute Eriocaulaceæ and Xyridaceæ. Under the clumps of shrubs were noticed small patches of Sphagnum, and a small species of Drosera closely resembling in form the common D. rotundifolia of
northern bogs. A very beautiful blue bell-gentian was common. This does not belong to the genus Gentiana, but to a related one, Chilonanthus. A few ferns were noted, among them the ubiquitous Pteris aquilina. The shrubby plants belonged mostly to the distinctly tropical families Malpighiaceæ, Melastomaceæ, Bubiaceæ and others.
Among the showiest flowers collected near the savanna, but at the margin of the forest, was an extremely beautiful rubiaceous shrub, which was not determined. Its large rose-colored bell-shaped flowers were produced in great profusion, and were most ornamental. A large purple Clitoria, an extremely showy papilionaceous creeper, was also common.
Much the most striking plant of the savanna, however, is a magnificent fan-palm, Mauritia fiexuosa, which occurs in groves of considerable size, making a very imposing sight.
Adjoining the savanna was a fairly dense forest, with comparatively dry soil, although there were numerous clear streams, deep amber brown in color, and in places it was decidedly boggy. As in all the forests, the palms formed the most conspicuous feature of the undergrowth. Ferns and liverworts were more abundant than in the forests near Paramaribo, and at the base of some of the trees a small Trichomanes was not uncommon, the only Hymenophvllaceæ that were collected. An interesting tree of this forest was the "Balata," a species of Mimusops which yields rubber of fair quality, which is collected in considerable quantities by the natives. There also occurs a species of Hevea, which, however, is much inferior in its product to the Para rubber tree. A not uncommon plant of this forest—and also seen repeatedly elsewhere—is Ravenala Guianensis, much resembling the well-known "traveller's palm," R. Madagascariensis. There was also the usual profusion of other Scitamineæ.
The flora of Surinam is remarkable for the abundance of showy flowers—not a usual condition of things in the wet tropics. Among the most conspicuous of these are many splendid climbing plants—especially various Bignoniaceæ, Apocynaceæ, Convolvulaceæ and Passifloraceæ. Some of these, like the golden yellow Allamandas and crimson and rose-colored passion flowers, were truly magnificent. There were also many showy shrubs, especially various Rubiaceæ, Malpighiaceæ and Melastomaceæ.
Of the herbaceous plants probably the showiest are the very abundant Heliconias. These look much like Cannas—or the larger ones like bananas—and their scarlet and yellow inflorescences are extremely brilliant. There were also great masses of red and yellow Cannas, and other showy Scitamineæ—e. g., Costus, Maranta, Thalia, etc. These brilliant flowers occurred in great masses along the margins of the forest, and the railway embankment was a veritable botanical garden.
Associated with these distinctly tropical plants were a number of more familiar aspect. The well-known red and yellow Asclepias curassavica was extremely common, and several species of Verbenaceæ and Composite were quite like northern forms.
Next to the palms, perhaps the most characteristic plants are the Araceæ, which occur in great number and variety. Besides those already referred to, perhaps the most noticeable were species of Caladium, whose brightly colored leaves were a common feature of low ground everywhere.
Of the epiphytic plants, the Bromeliaceæ take first place. There are also many species which grow upon the ground and closely resemble pineapples in their general appearance.
Surinam is not specially rich in orchids, and of these very few were in flower when the writer visited the country. The most interesting form encountered was a species of Catasetum (C. fuliginosum), already referred to.
As might be expected, aquatic plants are very numerous. Owing to an abnormally dry season prevailing during the early part of the year which dried up many bodies of water, comparatively few of these were in flower. Azolla was abundant in the ditches and canals, and also a species of Salvinia. The leaves of water lilies were abundant, but no flowers were seen. About the margins of ponds were sometimes seen the big white flowers of Hymenocallis obtusata, looking like white lilies.
Although Trinidad is reckoned with the West Indies, its flora is very different from that of the Antilles, and is essentially South American in type. Trinidad is separated from the mainland of Venezuela by only a few miles and the plants are largely the same as those in the adjoining regions of Venezuela and have much in common with those of the Guianas.
During a stay of two weeks the writer visited only the northern part of the island. This is, however, the most interesting portion of Trinidad, as not only are the highest mountains here, but there is also a fine development of lowland forest, and a savanna formation much like that seen in Surinam.
Port of Spain is perhaps the most attractive of the West Indian towns, and offers much of interest to the botanist—both in the town itself and in the environs. The botanical garden in Trinidad is the best in the West Indies, and in addition to the many fine examples of tropical plants cultivated in the garden there is adjoining it a considerable tract of practically untouched jungle, which is easily accessible and is full of interest to the visiting botanist. The garden is now under the direction of Mr. W. Freeman, to whom the writer is under obligations for much kind assistance during his stay in Trinidad.
Close to the old botanical garden is the more recently laid out agricultural experiment station, where are to be seen many varieties of the principal tropical fruits, especially oranges and mangoes. The latter are especially fine in Trinidad.
Among the most striking features of the botanical garden are the palms, of which there are many magnificent specimens, both native and exotic. In the town itself palms are planted in great numbers, especially the stately cabbage palm "palmiste" of the French Creoles, probably the finest of all palms. It is a common sight to see clumps of epiphytic orchids attached to the trunks of trees in the gardens of Port of Spain. These are said to be very beautiful during the early winter, but in July only a very few were in blossom.
In Port of Spain there are magnificent trees in the parks and gardens and along the roads. These are often of enormous size, and their branches are frequently covered with epiphytes of various kinds, among which the most conspicuous are the Bromeliads, and the curious Rhipsalis Cassytha, a member of the Cactaceæ, but very different from most of the family. This plant grows in immense pendent masses, sometimes ten feet or more in length, and is exceedingly common in Trinidad. Of the numerous large trees, the silk-cotton (Ceiba), the West Indian cedar (Cedrela odorata), and the sand-box (Hura crepitans) were the commonest of the native species; but mahogany trees of large size, and gigantic specimens of Pithecolobium Saman, are frequently seen. A very curious native tree, Couropita guianensis, is sometimes seen planted. This produces many short branches from the main trunk, upon which the large red flowers are borne in great numbers. These are followed by enormous globular fruits of such size as to fairly entitle the tree to its popular name, "cannon-ball" tree. Space will not permit of any further enumeration of the beautiful and curious plants with which the gardens are filled.
Much of the country about Port of Spain is still but little disturbed, and even where it has been cleared, the neglected land soon reverts to jungle. The wetter lowlands abound in palms, Aroids, Scitamineæ, etc., much the same types that occur in the Guiana forest. The drier hillsides, however, show a good many forms different from those of the lower levels. A very common palm of the dry hillsides is Acrocomia sclerocarpa, a species common to the Antilles also, and very common in Jamaica. A very showy shrub of this region is a rubiaceous plant, Warscewiczia coccinea. In this plant, as in the related Mussaenda of the eastern tropics, one of the calyx lobes is much enlarged and petallike in color and texture. In Mussaenda this is white, but in Warscewiczia it is a vivid carmine red, and the whole inflorescence strongly suggests the familiar poinsettia—indeed the plant is locally known as wild poinsettia.
Ferns are much commoner in Trinidad than in Guiana, although at the lower levels they are not especially notable. Two species of Schizæaceæ were common near Port of Spain—a Lygodium sp. and Anemia phyllitidis.
A visit to a small waterfall a few miles away yielded a considerable number of ferns, including some small Hymenophyllaceæ and a Danœa, and also several interesting liverworts. In the botanical garden were also found two interesting liverworts, a large Riccia and a Notothylas (?).
While driving to the waterfall a fine white arum (Spathiphyllum cannæfolium) was seen in great numbers along the river, and the trail to the falls led through a fine forest with tall trees and a luxuriant undergrowth of large ferns, some of which were small tree-ferns. There were also many Aroids, some of great size—Montrichardia sp., Philodendron, Anthurium, etc. Some very showy Bromeliads, with fine scarlet bracts, were common as epiphytes, and also a good many orchids; but some of the latter were in flower. These, with the gorgeous Warsczewiczia and masses of the fine Heliconia Bihæ, made a magnificent picture of tropical vegetation in its most luxuriant aspect.
Small tree ferns (species of Alsophila and Hemitelia) were fairly abundant, and several young specimens of a Danaea were found on a wet bank, where there was also found a luxuriant growth of several interesting liverworts. The latter included species of Aneura, Metzgeria, Symphyogyna (?), Fossombronia and Dumortiera.
In company with Mr. Freeman, assistant director of agriculture, a very interesting excursion was made to the Aripa savanna, some 25 miles from Port of Spain. This savanna was in many respects like the one visited in Surinam, but the vegetation was more luxuriant. There were similar groves of Mauritia, but even a finer species (M. setigera). A number of beautiful ground orchids were found in flower, and a small Drosera, different from that found in Surinam, was common. Tiny Utricularias with yellow and purple flowers were abundant, and as in the Surinam savannas, there were clumps of low bushes, largely Melastomaceæ and Malpighiaceæ, in the shelter of which was found a very interesting fern, Schizæa pennula, as well as several other ferns. Two species of Lycopodium., L. cernuum and L. Carolinianum, were common.
The forest adjoining the savanna was very beautiful, with fine palms—Euterpe, Bactris, Attalea, Maximiliana, and others. A Commelynaceous plant with yellow flowers was very abundant (the same species was also seen in Surinam) and there were the usual abundant epiphytic orchids and Bromeliads, as well as a number of small Hymenophyllaceae.
In these woods were many specimens of a Clusia, growing first as an epiphyte, and sending down aerial roots, which finally completely strangle the tree upon which the Clusia has fastened itself. These parasitic trees, with their glossy magnolia-like leaves are extremely handsome, and much resemble in general appearance the species of Ficus, so common in the eastern tropics, which have the same habit of strangling the tree which gives them support.
Trinidad has no very lofty mountains, the highest peak, Tucuche, being very little over 3,000 feet. The most interesting excursion made was to this mountain. In company with Mr. Freeman, Mr. Urich, the government entomologist, and Mr. Chandler, an English botanist visiting Trinidad, the writer made the ascent of the mountain which offers no difficulties, and many interesting plants not found in the lower country were seen.
The route at first lay through extensive cocoa plantations, which occupy much of the lower forest lands in Trinidad. Along the margins of the streams the showy Aroid, Spathiphyllum cannæfolium, made a fine show, and another conspicuous and interesting plant was the curious Cyclanthus bipartitus, a member of the small family Cyclanthaceæ, whose systematic position is something of a puzzle to the systematist.
Lygodium sp. and Anemia phyllitidis, characteristic ferns of the lower country, were abundant, and a number of other ferns were noted as well as a few liverworts. These, however, are much better developed at higher elevations where there are a number of species of tree ferns belonging to the genera Alsophila, Cyathea and Hemitelia. None of these attain large proportions, and neither in the number of species nor in the size of individuals can Trinidad compare with Jamaica.
At an elevation of about 1,500 feet the primitive forest begins—characterized by magnificent tall trees, whose species in most cases could not be determined. The dense undergrowth comprised large ferns, palms, Heliconia, Araceæ of various kinds, and many shrubs and lianas, the whole forming a magnificent example of a wet tropical forest. That it was a "rain forest" we thoroughly appreciated, as we passed through it in a veritable tropical downpour which soon made every little ravine and gulley the bed of a torrent, and much of the time we had to wade through these small cascades when they crossed the trail.
However, although thoroughly drenched, we finally reached the summit where there is a shelter hut in which we were to pass the night. The rain ceased for the time being, and after a change into dry clothes the afternoon was spent exploring the upper part of the mountain.
Among the most noticeable plants of the summit were many Bromeiiaceæ, mostly epiphytes, but some of them growing on the ground. The scarlet and yellow bracts of some of these were extremely showy. Several species of palms were abundant, and especially Geonoma sp. confined to the higher elevations. One of the most beautiful plants met with was a species of Utricularia, U. montana, sometimes seen in cultivation. Unlike most of the genus, this is an epiphyte, and the drooping racemes of big white flowers might very well be mistaken for an orchid.
As is usual at the higher elevations in the tropics, the lower plants are relatively more abundant than at lower elevations. Besides, the tree ferns there were many others, including several Hymenophyllaceæ and two species of Danæa, which were growing abundantly upon the wet banks, and whose large liverwort-like prothallia were found in quantity. The wet banks also yielded a fair number of liverworts, and at the very summit the ubiquitous Lycopodium cernuum was abundant. Mosses and lichens also abounded, but no notes were made of the species.
To the botanist visiting this region for the first time, the abundance and variety of the palms will first attract attention. Many of them are exceptionally beautiful, and they often grow in large masses giving a characteristic stamp to the forest vegetation. Palms are a far more conspicuous feature in the South American tropical forest than in any part of the eastern tropics with which the writer is acquainted. The Araceæ, also, are more numerous and varied than in the tropics of the old world, and none of the old-world forms can rival the giant scandent genera, like Philodendron and Monstera, which are so characteristic of the American tropical forests.
Of the numerous Scitamineæ the common Heliconias with their gorgeous inflorescences will first attract attention, and of course the peculiarly American family, Bromeliaceæ, will be of special interest to the European visitor.
The prevalence of showy flowers in Surinam was noteworthy, as this is not a common feature in the wet tropics, a fact frequently commented on by scientific travelers. Whether or not the two go together, it may be mentioned that in Surinam there is also an extraordinary abundance of brilliant butterflies, some of them of wonderful beauty.
In Trinidad the prevalence of showy flowers was much less marked than in Surinam, although it is by no means deficient in striking flowers. As has already been stated, Trinidad in the main features of its flora belongs rather with the continental region of South America than with the other islands of the West Indies.