A herb. It grows 40-100 cm tall. There are lines along the stems. The leaves are narrowly sword shaped and 3-7 cm long by 2-5 mm wide. They are hairy underneath. The flowers are in groups near the top of the plant or in the axils of leaves. The flower petals are white.
Stems 40-100 cm, glabrous or papillate. Leaf blades 1-8 × 0.3-1 cm, margins glandular-dentate. Flowers: sepals 4-5 mm; petals 1-1.5 times as long as sepals. Capsules globose-ovoid, 3 mm, shorter than calyx. Seeds 1.8-2 mm. 2n = 34, 68 (both Asia).