Castanopsis megacarpa is a species of tree which could grow to a height up to 36 m and a bole diameter of 90 cm. The grey outer bark is smooth or shallowly fissured and the yellow inner bark is fibrous. Its sapwood has a white or pale-yellow colour. The twigs are thinly lenticellate or sometimes smooth. The leaves are elliptic-oblong in shape with a thick leathery texture and shining surface. Female flowers are placed singly along the rachis with acute perianth lobes whilst male flowers are distributed in clusters of 3 along the rachis with obtuse perianth lobes. Each ellipsoid cupule holds only one ellipsoid seed with a thick and woody wall. The timber of this species can be used to make bowls and other domestic utensils (Soepadmo & Saw, 2000).

Castanopsis megacarpa is located in primary and secondary mixed dipterocarp, kerangas to lower montane forests at an altitude of 1400 m. It can be found in Peninsular Malaysia, Singapore and Borneo. In Sabah, it is known from the districts of Sipitang, Beaufort and Ranau. In Sarawak, it is known from Bintulu, Kuching and Lundu (Mt. Pueh) districts (Soepadmo & Saw, 2000).