Tabernaemontana rotensis is a medium-sized tree, 8 to 10 m (26 to 33 ft) tall, in the Apocynaceae (dogbane) family. Thin, light green, opposite, elliptic-oblong leaves are 15 to 30 cm (5.9 to 11.8 in) long and 5 to 10 cm (2 to 4 in) wide. Sap is copious and milky. The inflorescence is an elongate, slender, few-flowered cyme about as long as the leaves, branched 3 to 4 times. The calyx has 5 narrow lobes about 5 mm (0.2 in) long, lobes overlapping to the left, with about five yellow glands at the base of each lobe. The corolla is white with lobes 1.4 cm (0.6 in) long and 4 mm (0.2 in) wide. Fruits are twinned or single, beaked, nearly 3 cm (0.6 in) long and 1 cm (0.4 in) thick, and 4 mm (0.2 in) long seeds are embedded in bright red pulp.