Annuals, rarely perennials. Petioles of stem leaves 0.5-1 mm, entirely connate. Calyx keeled or winged. Plicae asymmetrical, very oblique. Style filiform, longer to slightly shorter than the ovary. Capsules cylindric, wingless. Seeds triquetrous with three winged edges, rarely wingless or areolate; seed coat reticulate.

Fourteen species: Asia; 12 species in China.