PDF - Wallace Online

TROPICAL NATUREcan be put to uses which, if ordinary wood were used, wouldrequire hours or even days of labour. There is also a regularityand a finish about it which is found in hardly any otherwoody plant; and its smooth and symmetrically ringedsurface gives an appearance of fitness and beauty to itsOn the whole, we may perhaps considervaried applications.it as the greatest boon which nature givesto the natives ofthe eastern tropics.MangrovesAmong the forms of plants which are sure to attractattention in the tropics are the mangroves, which growbetween tide-marks on coasts and estuaries. These are lowtrees with widely-spreading branches and a network of aerialroots a few feet above the ground but their most remarkable;peculiarity is, that their fruits germinate on the tree, sendingout roots and branches before falling into the muddy soila completely formed plant. In some cases the root reachesthe ground before the seed above falls off. These treesgreatly aid the formation of new land, as the mass of aerialroots which arch out from the stem to a considerable distancecollects mud and floating refuse, and so raises and consolidatesthe shore ;while the young plants, often dropping fromthe farthest extremity of the branches, rapidly extend thedomain of vegetation to the farthest possible limits. Thebranches, too, send down slender roots like those of thebanyan, and become independent trees. Thus a completewoody labyrinth is formed ;and the network of tough rootsand stems resists the action of the tides, and enables themud brought down by great tropical rivers to be convertedinto solid land far more rapidly than it could be withoutthis aid.Sensitive PlantsAmong the more humble forms of vegetation that attractthe traveller's notice none are more interesting than thesensitive species of Mimosa. These are almost all natives ofSouth America, but one species, Mimosa pudica, has spreadto Africa and Asia, so that sensitive plants now abound aswayside weeds in many parts both of the eastern and westerntropics, sometimes completely carpeting the ground with