Pteralyxia macrocarpa, a member of the dogbane family (Apocynaceae), is a tree 8 to 15 m (26 to 49 ft) tall. Leaves are dark green and shiny on the upper surface, paler and dull on the lower surface, often brittle, and very broadly elliptic to obovate to suborbicular with blades (9) 9.2 to 18 cm (3.6 to 7 in) long, 4.5 to 7.7 cm (1.8 to 3 in) wide. Leaf margins are revolute or flat with the apex acute to rounded, petioles are 2.3 to 4.5 cm (0.9 to 1.8 in) long. Each leaf axil has a single scale-like gland that has brownish secretions. Pale yellow flowers are in groups of five, with lobes about 2 mm (0.08 in) long and corolla tubes 7 to 9 mm (0.3 to 0.4 in) long. The fruit is a large, bright red (at maturity) drupe (endocarp and exocarp surround a single seed) with two fruit per flower. The endocarp is woody and boat-shaped with the central and lateral wings or ridges prominent, 3 to 15 mm (0.1 to 0.6 in) high.