Trees, often growing to enormous size; Branchlets usually strongly longitudinally ribbed when young, occasionally weakly so. Leaves in whorls; Inflorescence of umbelliform or paniculate cymes; Sepals with colleters inside; Stamens free from the style head; Fruit of paired, divergent follicles, these heavy and woody, dehiscing at maturity. Seeds elliptic, flattened;
southern Thailand present, western Malesia present
2 species in western Malesia andsouthern Thailand.
Both species were previously tapped for making rubber and for the manufacture of chewing gum but this industry has greatly declined. Both also have a soft and easily worked timber but which is not durable. The wood is used for smaller items like pencils, picture frames, carving, toys, furniture parts, packing cases etc.
Monach. - in Lloydia. 1946: 182
D.J. Middleton - in Fl. Thailand. 1999: 36
Pichon - in Mém. Mus. Natl. Hist. Nat. 1949: 190
K. Schum. - in Engl. & Prantl, Nat. Pflanzenfam. 4. 1895: 139
D.J. Middleton - in Gard. Bull. Singapore. 2003: 210
Backer & Bakh.f. - in Fl. Java. 1965: 227
Hook.f. - in PROSEA. 2000: 65
Hook.f. - in Tree Fl. Sabah & Sarawak. 2004: 27