Tree 10-20 m. Leaves membranous or chartaceous, elliptic to oblong-lanceolate, 12-30 by 4.5-12 cm, apex obtuse to acute-acuminate, base rounded, subtruncate, or short-attenuate, drying greenish to brown above; Inflorescences: Fruits 1-3 per infructescence, ovoid-ellipsoid or ellipsoid-oblong, apex and base subacute, 3-4 by 1.4-2 cm, at first with minute indumentum, early glabrescent, leaving a finely granulate surface;
Asia-Tropical: Malaya (Peninsular Malaysia present); Sumatera (Sumatera present), Kelantan present, Peninsular Thailand present, Perak present, Simeuluë I present
Peninsular Thailand; in Malesia: Sumatra (incl. Simeuluë I.) and Peninsular Malaysia (Perak, Kelantan).
Knema sumatrana is closely related to K. glauca; several of the stouter specimens included in K. glauca are difficult to separate from K. sumatrana. Possibly these specimens are hybrids, with an intermediate habit. In most instances, however, K. glauca can easily be distinguished by the smaller size of twigs and leaves, smaller male flowers with fewer anthers (8-11, or in E Java up to 14), and by smaller fruits, 1.8-2.5(-4) cm long, as against 3-4 cm in K. sumatrana. Other characters of diagnostic value of K. sumatrana are the early glabrescent twig apex and lower leaf surface, persistent brac-teole, many (12-18) distinctly stiped anthers, somewhat convex, finely papillate staminal disc, narrow connective, and almost laterally opening thecae.