The ferns, although abundant, especially in moist woods from Alaska southward, throughout the continent, reach their greatest variety and richest luxuriance in the West Indies and Central America, where the graceful and most artistically beautiful tree-ferns add an indescribable charm to the always varied foliage. The tree-ferns grow farther up the mountains of the torrid zone than do the larger palms (in the same manner that the smaller ferns extend much farther north than the most hardy palmettoes), and form a conspicuous feature in the foreground of nearly every wide-reaching prospect in the more elevated portions of the West Indies, Central America, and south-central Mexico. In addition to the palms and ferns, the tropical forests of North America contain a large number of trees of great economic importance. Chief among these are the mahogany, which is native to the lands bordering the Caribbean Sea and Gulf of Mexico, and reaches the largest size and produces the most beautiful and most highly prized wood on Cuba, Haiti, the Bahamas, and Jamaica. As is well known, this hard, dark, heavy, fine-grained, and exceedingly durable wood has been used for the best grades of cabinet-work for about two centuries, and is still unsurpassed for the beauty of its grain, susceptibility of a high polish, and the several ways in which it is adapted for the carver's tool. On account of the great and long-continued demand for its wood it has become scarce in all but the most inaccessible localities. When allowed to reach full maturity it is a large, wide-spreading tree with numerous branches, looking not unlike a giant oak, but has pinnate leaves and small, although somewhat conspicuous, white flowers. Another gift of the tropical forest is the lignum-vitae, which furnishes the exceedingly tough, hard, resinous wood preferred above all others for the making of pulleys, mallets, etc. Many other highly prized woods, not known, however, by familiar names, are also found in the varied forests of tropical America, as well as numerous vegetable dyes, such as logwood, brazil-wood, indigo, etc. The lands of the Caribbean-Gulf region are credited with having introduced to civilized man the potato, Indian corn (maize), and tobacco, although the home of the former is probably in the Andean portion of South America. Indian corn grows luxuriantly not only in the hot lowlands of Mexico, but on the border of the central table-land of that republic, where it is supposed to be indigenous, and has now become one of the leading crops of temperate North America, and is cultivated in many other portions of the world. Tobacco was found under cultivation in Mexico at the time of the first coming of Europeans, and retains for its familiar name the appellation of the district where it was first seen. From Mexico also come the dahlia and the giant sunflower, as well as the various species of aloes and cacti now so common in gardens and conservatories the world over.