Viola lanaiensis is a member of the violet family (Violaceae) and is a small, erect, unbranched or little branched subshrub, 10 to 40 cm (4 to 16 in) tall. The leaves, which are clustered toward the upper part of the stem, are lance shaped, about 6 to 11 cm (2.4 to 4.3 in) long and 1.3 to 2.5 cm (0.5 to 1.0 in) wide. Below each leaf is a pair of narrow, membranous stipules, about 0.9 cm (0.4 in) long. The flowers are small, 1.0 to 1.5 cm (0.4 to 0.6 in) long, white tinged with purple or with purple veins, occurring singly or up to four per upper leaf axil. The fruit are capsules, about 1.0 to 1.3 cm (0.4 to 0.5 in) long.