Enum. Syst. Pl., 9. 1760.
Herbs, subshrubs, or shrubs, perennial, rhizomatous, without stinging hairs, sparsely to ± densely pubescent or tomentose with hooked, curved, or straight, nonstinging hairs on all parts of plant. Stems simple to freely branched, erect. Leaves opposite or nearly opposite, or alternate; stipules present. Leaf blades lanceolate to broadly ovate, base rounded to cordate, less often cuneate, margins dentate or serrate, apex acuminate; cystoliths rounded. Inflorescences axillary, spikelike or paniculate. Flowers unisexual, staminate and pistillate flowers on same plant, rarely on different plants, in remote or crowded clusters in same or separate inflorescence; bracts linear. Staminate flowers: tepals 4; stamens 4; pistillode globose. Pistillate flowers: tepals 4, connate, adnate to ovary; staminodes absent; style persistent, elongate; stigma linear, straight or hooked. Achenes sessile, laterally compressed, ovoid, nearly orbicular, or ellipsoid, tightly enclosed by persistent perianth. x = 14.
Tropical and subtropical regions worldwide.
Species 50 (2 in the flora).