Tree 10-20 m. Leaves membranous or chartaceous, oblong(-lanceolate), 30-45 by 9-15.5 cm, apex rounded, retuse, or acute-acuminate, base rounded to shallowly cordate, with the basal nerves somewhat crowded, drying greenish to blackish brown above, lower surface very finely papillate or not, with persistent short, dense, greyish brown or pale cinnamon hairs 0.2 mm long, silky to the touch, mixed with sparse somewhat stouter ones; Inflorescences: Fruits 1 or 2 per infructescence, subglobose to broadly ovoid, apex 1-2 mm beaked, 3.5-5 by 3.5-4 cm, with grey-brown to rusty scale-like hairs 0.1 mm long;
Asia-Tropical: Borneo present (Brunei present, Sarawak present), C & NE Kalimantan present
Malesia: Borneo (Sarawak: 1st Div.; Brunei; C & NE Kalimantan).
Knema sericea is related to K refusa, K. ashtonii (var. cinnamomea), and K elmeri, with which it has the dense silky indumentum on the lower leaf surface in common. Knema elmeri has similar, though smaller male flowers, also with a convex or mammillate staminal disc, and differs in the less stout habit of the twigs, with flaking bark. Knema retusa (Peninsular Malaysia) differs in its stout obtuse leaves and broad, subglobose or ovoid, ± apiculate fruits, and the pedunculate inflorescences. The short indumentum on the lower leaf surface in K sericea is more fluffy than that of K. ashtonii var. cinnamomea, for which it can easily be mistaken, but which has a quite different androecium.