Annuals, 2-10(-25+) cm. Stems branched ± throughout, ± strigillose to villous, glabrescent. Leaves petiolate or sessile; blades obovate to spatulate, 2-3-pinnately lobed (ultimate lobes narrowly spatulate to linear), (1-)2-3(-6) cm. Involucres 3-4(-6) mm diam. Phyllaries 13-22+ in 2-3 series, subequal (apices brown). Ray florets 0 (peripheral pistillate florets 8-80+ in 1-3+ series; corollas 0). Disc corollas ochroleucous to pale yellow, 0.5-0.8 mm. Cypselae: outer stalked, 1-1.2 mm, ± winged, faces ± papillate; inner sessile, 0.8-1 mm, not winged, not papillate. 2n = 36, 40. Flowering Jan-Sep. Disturbed sites; 0-800 m; introduced; Ariz., Calif., Fla., Maine, Oreg., Tex.; Australia; also introduced in Northern Hemisphere: Mexico (Baja California); South America; Africa.

Plant: Annual, ± aromatic; stems < 20 cm, very slender, branched from base, sparsely hairy Leaves: 2-6 cm, alternate, 2-3-pinnately divided into linear segments, petioled or upper sessile INFLORESCENCE: primary inflorescence a head, each resembling a flower; heads disciform, solitary, 3-6 mm diam; phyllaries in 2 series, margins scarious, tips brownish Flowers: Pistillate flowers in 2-3 series, borne on slender stalks; corolla 0; ovary flattened; Disk flowers few-many, sessile or subsessile; corolla ± 1 mm, pale yellow, tubular, 4-lobed; style and stamens included; anther tips ovate, bases rounded or ± cordate; style branches truncate with shrub-like tips Fruit: Fruit: marginal achenes ± 1 mm, widely winged, slightly < stalks; inner achenes < 1 mm, not or scarcely winged, ± sessile Misc: < 250 m.