Acmella Rich. ex Pers.

Annual or perennial herbs, erect or semiprostrate. Leaves opposite, sometimes clustered at base of stem. Capitula radiate or discoid, usually solitary, sometimes in groups of 2 or 3, terminal or axillary, ±ovoid, pedunculate; involucral bracts 1–3-seriate, subequal, usually broad, thin, at least outer ones leaf-like; receptacle conical, elongating in fruit; paleae membranous, loosely enfolding achenes. Ray florets usually present, 1-seriate, female. Disc florets bisexual, tubular, 4-or 5-lobed; anthers not or scarcely lobed at base. Ray achenes obovoid to ellipsoid, 3-angled. Disc achenes obovoid to ellipsoid, strongly laterally compressed, 2-angled, often ciliate on margins. Pappus absent or of 1–4 short fine bristles at angles of achene (bristles often hardly distinct from cilia).