FOREST TREES, Tropical. Most inter esting trees grow between the tropics, some of which have traveled quite around the globe. A vast number of economic products, exclusive of the more important tropical fruits, derived from them, have been carried far and wide since the dawn of commerce. The character of these forests varies greatly, influenced by waterfall and altitude. This is illustrated in Porto Rico where °the various formations in the order of their occurrence from the coast toward the interior are as follows: Littoral woodlands, moist deciduous forests, and tropical rainforests on the north or humid side, and the dry de ciduous forest on the south or semi-arid side.° These different formations overlap more or less, or disappear but are to be recognized everywhere in the tropics.
The most obvious difference lies between those trees growing on hot dry areas like the Liguanea plain in Jamaica, where rain falls perhaps twice a year and then in torrents, and those forming dense forests on the nearby mountains, where rain and fogs are frequent. In dry soil the trees grow sparsely, and are apt to be low and broad of head, with foliage subdivided, and sometimes armed with thorns. The leguminous tribe is usually well repre sented. In the jungle, however, the arbores cent growth is more interesting to the eye. The foliage is often evergreen, thick and glossy with waxen coatings designed to shed water, and simple of outline. In the heat and mois ture of these damp deciduous and tropical rain forests, as Colonel Roosevelt remarks, °The struggle for life among the forest trees and plants is far mote intense than in the North. The trees stand close together, tall and straight, and most of them without branches, until a great height has been reached; for they are all striving toward the sun, and to reach it they must devote all their energies to produc ing a stem which will thrust its crown of leaves out of the gloom below into the riotous sunlight which bathes the billowy green upper plane of the The trunks of these trees are usually pale gray or pallid in hue, and many of them have brilliant flowers such as those crowning the bois immortelle, which are, however, unsuspected by the stroller be neath, unless the forest floor be littered with gay petals fallen from their place under the sun, where only an aeronaut or mountain climber can see them. Huge vines or lianes, which rise upward with the trees that they em brace, are characteristic of these forests; some are as straight and thick as saplings, others are twisted and contorted;'others cling insepa rably to the boles. Some clothe the tree-trunks with verdure, others hang naked like ropes dangling from a ship's rigging. The trees are moreover loaded with masses of epiphytic plants, ferns and mosses. Orchids form huge tufts, or trail in long flowering streamers, and stiff wild pines hold water in the cup-like bases of their leaves in which little batrachians bathe. These features are most easily seen
at the edges of clearings laboriously hacked out with cutlass or machete for garden patches. Tropical forests are continuously destroyed and steep hills left bare for the action of erosive forces, by these small cultivators who supply most of the constant supply of green stuff used in towns. They cut down the giant trees with all their burdens and either consume them in charcoal kilns or in huge bonfires that are a characteristic sight among the mountains, burning like beacons night and day, and often burning over more territory than is required. The ashes supply fertilizer, and when the ground is exhausted in a few years the gar deners repeat theprocess.
As in the north, certain tropical trees are notable. Such are the banyan •(Ficus Benga lenses), an individual tree soon becoming an umbrageous grove by sending down roots from its branches, and its near relative, the sacred bo-tree, or peepul (Ficus religiosa) in whose ever-quivering foliage dwell Indian gods. Sometimes eccentric growth, like those swollen trunks of bottle trees (Sterculia) of Australia, makes them noticeable or some peculiar usage, as when the easily-hollowed trunks of baobabs (Adansonia digitata), are utilized for cisterns for storing water caught in near-by tanks dur ing the rainy season — an adaptation of great service during the recent campaigns in Africa. Often it is the flowers that attract, as is the case of the flaming Spathodea Nilotica, or of the royal poinciana (Poinciana regia). The succulent, golden corollas of the Indian mahwa (Bassia latifolia), falling profusely, bring the peasantry in crowds to feast on the fleshy petals, that sometimes save them from starva tion, and to distil from them a nauseous intoxi cating liquor. The sacred and fragrant asoka (Saraca Indica) and champaca (Michelia Champoca), on account of their flowers are planted about Eastern temples for ceremonial use. The delightfully-scented flowers of the latter are used as a cheap drug and are also the source of a perfume said to be substituted for that of the more valuable ylang-ylang (Can anga odorata), a huge tree of the Philippines, whose tassel-like flowers retain their odor even when dried and were hawked about the streets of Manila in trays for sachets. The fluffy, yellow flower-balls of several acacias, more particularly those of the aromo, huisache, cassie or popinac as the Acacia Farnesiana is vari ously denominated, are similarly plucked for their odor. Likewise, nearly the whole of the citrus tribe contribute essences for .perfumers' uses, as does also the Eucalyptus citriodora, and that very large South American tree, Dip teryx odorata, whose fruits — tonka beans were formerly scented snuff. Balsams of Peru and of Tolu (Myroxylon) and other fragrant gums and resins extracted from tropical trees, as well as the odorous heartwood of lign aloes (Aquilaria) and sandalwood (Santalum), find their way into perfumery.