Herbs, annual, not rhizomatous or stoloniferous. Stems prostrate to erect, branched; nodes glabrous. Leaves alternate, not articulate at base, somewhat to markedly clasping, attachment points linear; blade linear to oblanceolate, or ovate to spatulate, flattened, glabrous or with elongate unicellular hairs. Inflorescences racemose, somewhat to markedly secund (at least distally), elongate, bracteate; bracts leaflike. Flowers pedicellate; sepals persistent in fruit, imbricate, green, distinctly angled or keeled, ovate, herbaceous, glabrous or with elongate, unicellular hairs; petals usually 5, red; stamens 3–15, usually opposite petals, not adnate to petals; ovules 6–many; style present; stigmas 3. Capsules 3-valved, longitudinally dehiscent from apex, valves not deciduous, reflexed after dehiscence, margins markedly involute; endocarp and exocarp not separating. Seeds 10–20, black, ± ellipsoid, reticulate or tuberculate viewed at 30×, glabrous, estrophiolate. x = 12.
Temperate w Americas, with greater diversity in w South America.
Species 14 (2 in the flora).