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.
Essentially glabrous, somewhat succulent perennial 5-30 cm tall, often trailing; lvs sessile, with subscarious sheathing base, entire or with a few coarse teeth or deep narrow lobes, narrowly oblong or lanceolate to linear, 1-6 cm נ1-10 mm, or broader when lobed; heads solitary at the ends of the branches; disk 5-11 mm wide; pistillate fls in a single series, without cor; achenes of the outer fls broadly winged, shorter than the stipe, the others merely 2-nerved, short-stipitate, the stipes persistent on the receptacle; 2n=20. Tidal flats, wet meadows, and other moist places; native of S. Afr., occasionally found from Que. to Mass. in our range. July-Aug.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.