Perennials, (3-)5-15(-25+) cm tall or across. Stems prostrate (rooting at nodes, ± fleshy) to decumbent or erect, glabrous. Leaves sessile (bases sheathing stems); blades linear to lanceolate or oblong (sometimes lobed, lobes lanceolate to linear), (1-)2-3(-7) cm, ultimate margins entire or irregularly toothed or lobed, faces gland-dotted. Involucres 6-9(-12+) mm diam. Phyllaries 21-30+ in 2-3+ series. Ray florets 0 (peripheral pistillate florets 12-40+ in 1 series; corollas 0). Disc corollas yellow, 1-1.5 mm. Cypselae: outer 1.2-1.8 mm, winged, adaxial faces papillate; inner 0.7-1 mm, scarcely, if at all, winged, not papillate. 2n = 20. Flowering Mar-Dec. Saline and freshwater marshes, along streams; 0-900 m; presumed introduced; B.C., N.B., N.S., P.E.I., Que.; Alaska, Ariz., Calif., Md., Mass., Nev., Oreg., Wash.; S Africa, Australia; also introduced in Mexico (Baja California); South America; Europe.

Plant: Perennial, ± aromatic; stems generally < 50 cm, ± fleshy, glabrous, decumbent, rooting from nodes Leaves: 2-7 cm, alternate, linear to lanceolate or oblong, entire or irregularly toothed or lobed into widely linear to lanceolate divisions; base forming a fused sheath around stem INFLORESCENCE: primary inflorescence a head, each resembling a flower; heads disciform, solitary, 6-15 mm diam; phyllaries in 3 ± unequal series Flowers: Pistillate flowers in 1 series, borne on slender stalks; corolla 0; ovary flattened; Disk flowers many, small, subsessile; corollas ± 1 mm, bright 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 1.5-2 mm, widely winged, ± = stalks; inner achenes 1-1.5 mm, not or scarcely winged, nearly sessile Misc: < 300 m.