Gangaw (Messua ferrea) the Assam iron-wood, is suitable for sleepers; and didu (Bombax insigne) is used for tea-boxes and packing-cases.
The most striking trees in the forest region are, in the basin of the Cavalla, the giant Funtumia elastica, which grows to an altitude of 200 ft.; various kinds of Parinarium, Oldfieldia and Khaya; the bombax or cotton tree, giant dracaenas, many kinds of fig; Borassus palms, oil palms, the climbing Calamus palms, and on the coast the coconut.
The arboreous forms which least require the humid and equable heat of the more truly tropical and equatorial climates, and are best able to resist the high temperatures and excessive drought of the northern Indian hot months from April to June, are certain Leguminosae, Bauhinia, Acacia, Butea and Dalbergia, Bombax, Shorea, Nauclea, Lagerstroemia, and Bignonia, a few bamboos and palms, with others which extend far beyond the tropic, and give a tropical aspect to the forest to the extreme northern border of the Indian plain.
The beautiful ceiba (Bombax ceiba L., Ceiba pentandra) or silk cotton tree is the giant of the Cuban forests; it often grows to a height of 100 to 150 ft.
Among other forest trees of economic importance are the silk-cotton tree (Bombax ceiba), the Palo de vaca, or cow-tree (Brosimum galactodendron), whose sap resembles milk and is used for that purpose, the Inga saman, the Hevea guayanensis, celebrated in the production of rubber, and the Altalea speciosa, distinguished for the length of its leaves.