Like the mosses and lichens of our woods, parasites of endless variety and almost inconceivable size and luxuriance (ferns, bromelias, tillandsias, orchids, and pothos) cover in the tropical zone the trunks and branches of the forest trees, forming hanging gardens, far more splendid than those of ancient Babylon. While the orchids are distinguished by the eccentric forms and splendid colouring of their flowers, sometimes resembling winged insects or birds, the pothos family (caladium, calla, arum, dracontium, pothos) attract attention by the beauty of their large, thick-veined, generally arrow-shaped, digitated, or elongated leaves, and form a beautiful contrast to the stiff bromelias or the hairy tillandsias that conjointly adorn the knotty stems and branches of the ancient trees. In size of leaf, the Pothos family is surpassed by the large tropical water-plants, the Nymphæas and Nelumbias, among which the Victoria regia, discovered in 1837 by Robert Schomburgk in the river Berbice, enjoys the greatest celebrity. The round light-green leaves of this queen of water-plants measure no less than six feet in diameter, and are surrounded by an elevated rim several inches high, and exhibiting the pale, carmine red of the under surface. The odorous white blossoms, deepening into roseate hues, are composed of several hundred petals; and, measuring no less than fourteen inches in diameter, rival the colossal proportions of the leaves. The Victoria is found all over the Amazon district, but rarely or never in the river itself. It seems to delight in still waters, growing in inlets, lakes, or very quiet branches of the river fully exposed to the sun. [Illustration: BOTTLE-TREE.] The trunk of several tropical trees offers the remarkable peculiarity of bulging out in the middle like a barrel. In the Brazilian forests, the Pao Barrigudo (_Chorisia ventricosa_) arrests the attention of every traveller by its odd ventricose shape, nearly half as broad in the centre as long, and gradually tapering towards the bottom and the top, whence spring a few thin and scanty branches. It is only by seeing great numbers of these trees all with their character more or less palpable, that one can believe it is not an accidental circumstance in the individual tree, instead of being truly characteristic of the species. The Delabechea, or bottle-tree, discovered by Mr. Mitchell in tropical Australia, has the same lumpish mode of growth. Its wood is of so loose a texture that, when boiling water is poured over its shavings, a clear jelly is formed, and becomes a thick viscid mass.