Acnida Linnaeus, Sp. Pl. 2: 1027. 1753; Gen. Pl. ed. 5, 452. 1754; Acnida sect. Acnidastrum Moquin-Tandon; Acnida sect. Montelia Moquin-Tandon

Plants annual, glabrous. Bracts not enfolding flower, not leaflike, narrowly elliptic to subulate-linear, margins entire, plane (or in some species indistinctly undulate). Pistillate flowers: tepals absent or 1-2, reduced-linear or linear-lanceolate. Utricles usually indehiscent (dehiscent in some forms of A. tuberculatus).

Species 4 (4 in the flora): North America, Mexico, West Indies, South America.