Psychotria hexandra var. oahuensis, a member of the coffee family (Rubiaceae), is a shrub or tree up to 6 m (20 ft) tall. Leaves are membranous, chartaceous (papery), or coriaceous (leathery), obovate to oblanceolate, 1.2 to 8.3 in (3 to 21 cm) long, 0.5 to 3.5 in (1.3 to 9 cm) wide, lateral veins in 7 to 12 pairs, domatia (leaves modified to form small chambers) small and inconspicuous, apex acute and often with a very pronounced, acute tip, base acute or attenuate (tapering), petioles (leaf stalks) 0.4 to 3 cm (0.15 to 1.2 in) long at base, stipules (leaf basal appendage) irregularly obovate, up to l5 mm (0.6 in) long. Flowers are functionally unisexual, usually in groups of six, inflorescences either with one main axis or 2- to 3-branched from the base, up to 12 cm (4.7 in) long, twice branching determinate inflorescence. Fruit are broadly ellipsoid, 8 to 15 mm (0.3 to 0.6 in) long (not including the persistent calyx tube). Two varieties of Psychotria hexandra are recognized: variety hexandra, only found on Kauai, and variety oahuensis, found on Oahu. The variety oahuensis is differentiated from variety hexandra by its acutely-apexed white corolla in bud, stigmas of functionally pistillate flowers 3 to 6 mm (0.1 to 0.2) long, and cylindrical. Its ventral surface is often flattened and has blunt projections or short hairs.