Santalum involutum is a small tree in the Santalaceae (sandalwood) family, 4 to 8.3 m (13 to 27 ft) tall and glabrous with smooth, charcoal-colored bark. Coriaceous (papery), opposite leaves, often drooping, are 5.7 to 8 cm (2.2 to 3 in) long, 1.4 to 1.8 cm (0.6 to 0.7 in) wide, linear-elliptic, with sides rolled in so they appear tubular. Cymes (inflorescences with terminal flower blooming first) are 3 to 5 cm (1.2 to 2 in) long, and 5- to 15-flowered; peduncle (flower stalk) 9 to 16 mm (0.4 to 0.6 in) long, with campanulate (flaring) to cylindrical four lobed flowers that are greenish-white (sometimes turning red with age). Drupes (fleshy single-seeded fruit) are 15 to 20 mm (0.6 to 0.8 in) long with an apical ring and slender tip 3 to 5 mm (0.1 to 0.2 in) long.