Viola oahuensis, a member of the violet family (Violaceae), is usually an erect, unbranched subshrub 6 to 40 cm (2.4 to 16 in) tall. The papery-textured leaves are usually 3 to 12 cm (1.2 to 4.7 in) long, 2.5 to 5.8 cm (1 to 2.3 in) wide, and elliptic-egg-shaped to elliptic. The leaf stalks are typically 0.5 to 1 cm (0.2 to 0.4 in) long. The narrowly triangular stipules are usually 10 to 15 mm (0.4 to 0.6 in) long, 3.5 to 6 mm (0.1 to 0.2 in) wide, and have fringed edges. One to two flowers are borne on stalks typically 25 to 60 mm (1 to 2.4 in) long. The petals are pale yellow, the upper ones 8 to 13 mm (0.3 to 0.5 in) long, the lateral ones 10 to 13.5 mm (0.4 to 0.5 in) long, and the lower one 12 to 16 mm (0.5 to 0.6 in) long. The capsules are 9 to 16 mm (0.4 to 0.6 in) long. This species is distinguished from other Hawaiian members of the genus by the stipule characters, the length of the leaf stalks, and the length and papery texture of the leaves