Description from Flora of China
Herbs perennial. Rhizomes absent. Stems creeping or decumbent proximally. Leaves distichous or spirally arranged. Cincinni terminal and/or axillary, paired or aggregated, less often solitary; involucral bracts not spathelike; pedicels very short. Flowers actinomorphic. Sepals 2 or 3, free. Petals 2 or 3, free, lanceolate. Stamens (1--3 or)6, all fertile, very rarely 1 or more becoming staminodes, subequal; filaments usually glabrous; anther locules rounded, longitudinally dehiscent, connectives broad and square, triangular, or oblong, rarely narrow. Ovary oblong, subtrigonous, 2- or 3-loculed; ovules 2 per locule. Capsule 2- or 3-valved. Seeds (1 or)2 or 3 per valve, shortly cylindric, trigonous, rugose or radiate striate; hilum orbicular, minute.
About 20 species: America; one species (introduced) in China.