Description from Flora of China
Herbs or subshrubs, perennial. Rootstock slightly woody. Stems branching near base, ascending, 20--30 cm, pilose. Stipules white, long triangular, 1.5--2 mm, scarious. Leaves opposite or apparently verticillate; leaf blade narrowly oblong to oblong-elliptic, 5--20 × 1--3.5 mm, distinctly shorter than internode, glabrous, mostly sharply reflexed from base, apex obtuse, mucronate. Cymes rather lax; bracts scarious. Pedicel mostly short, to 5 mm in fruit, with sparse long hairs. Flowers ca. 4 mm. Sepals white, with thick brown veins near base, ovate, ca. 3 × 1.5 mm, apex acuminate. Petals white, with purple-brown veins, longer than sepals. Stamens usually 5, subequaling sepals. Style filiform, 1--2 × as long as ovary. Capsule brown, ovoid, ca. 3 mm, glossy. Seed brown, ca. 0.7 × 0.3 mm. Fl. May--Jul, fr. Aug--Oct.
The collections from Hainan are very uniform, with distinctively reflexed leaves and well-developed, brown veins at the bases of the sepals. Material from Vietnam is more variable, rarely showing the reflexed leaves and with more indistinct sepal venation, and is difficult to separate from the rather variable Polycarpaea arenaria (Loureiro) Gagnepain.
Most records from coastal sands, also recorded from grasslands on mountain slopes. Guangdong, Hainan [Cambodia, India, Malaysia, Vietnam].