Tree to 15 m or more. Branchlets purplish brown, pubescent or glabrous. Leaves firm and papery, (7–)11–20 × 3–5 cm, ovate, lanceolate or narrowly oblong, 13–19 secondary veins on each side of the midrib, margins with two to five shallow teeth towards the apex, apex long-acuminate; petiole 0.8–1.5 cm long. Pistillate inflorescences to 20 cm long with three flowers per cupule. Cupules subglobose, 3 cm diameter and yellowish grey with small, reddish brown, waxy trichomes; bracts spine-like, 0.5–0.8 cm long, often connate into bundles. Nuts (one to) two to three per cupule, 2–2.5 × 1–1.5 cm, hairy. Flowering July to September, fruiting August to October of the following year (China). Huang et al. 1999. Distribution CHINA: southeast Xizang, western Yunnan; INDIA: Assam, Sikkim. Habitat Evergreen, broadleaved forest between 900 and 1700 m asl. USDA Hardiness Zone 8–9. Conservation status Not evaluated.
Castanopsis wattii is known in cultivation only from a few seedlings grown from an Allen Coombes collection (Coombes 512) made in Yunnan between Manwan and Jing Dong, in evergreen woodland at 2040 m in 1998, from a tree about 15 m tall.