PDF - Wallace Online

248 TROPICAL NATUREBesides these various kinds of trees and climbers, Avhichform the great mass of the equatorialforests and determinetheir general aspect, there are a number of forms of plantswhich are always more or less present, though in some partsscarce and in others in great profusion, and which largely aidin giving a specialcharacter to tropical as distinguished fromtemperate vegetation. Such are the various groups of palms,ferns, ginger-worts, and wild plantains, arums, orchids, andbamboos ;and under these heads we shall give a short accountof the part they take in giving a distinctive aspect to theequatorial forests.PalmsAlthough these are found throughout the tropics, and afew species even extend into the warmer parts of the temperateregions, they are yet so much more abundant andvaried within the limits of the region we are discussing thatthey may be considered as among the most characteristicforms of vegetation of the equatorial zone. They are, however,by no means generally present, and we may passthrough miles of forest without even seeing a palm. In otherparts they abound either ; forming a lower growth in thelofty forest, or in swamps and on hillsides sometimes risingup above the other trees. On river-banks they are especiallyconspicuous and elegant, bending gracefully over the stream,their fine foliage waving in the breeze, and their stems oftendraped with hanging creepers.The chief feature of the palm tribe consists in thecylindrical trunk crowned by a mass of large and somewhatrigid leaves. They vary in height from a few feet to that ofthe loftiest forest trees. Some are stemless, consisting onlyof a spreading crown of large pinnate leaves ;but the greatmajority have a trunk slender in proportion to its height.Some of the smaller species have stems no thicker thana lead pencil, and four or five feet high; while the greatMauritia of the Amazon has a trunk full two feet in diameter,and more than one hundred feet high. Somespecies probably reach a height of two hundred feet, forHumboldt states that in South America he measured apalm, which was one hundred and ninety-two English feet