Plants (1-)2-5(-25+) cm (high or across), ± villous, glabrescent (not stoloniferous, stems purplish, prostrate to ascending, often rooting at nodes). Leaves basal and cauline; blades ± oblanceolate, 1-2(-3)+ cm, 2(-3)-pinnati-palmately lobed. Heads mostly scattered along stems. Involucres 2-4(-5) mm diam. Pistillate florets 5-8(-17+) in 1-2+ series. Disc florets 4-8+; corollas 1.5-2.5 mm. Cypselae: bodies ± obovate to lanceolate, (1.5-)2.5-3+ mm, usually winged (wings entire or ± sinuate to incised, each shoulder usually distally projecting as spinelike tooth), faces glabrous or ± scabrellous to hirtellous; pappi 0 (persistent stylar sheaths indurate, spinelike, 1-2+ mm, erect or slightly inflexed). 2n = ca. 92 (as S. pterosperma), 110+ (from Portugal), 118-120.

Flowering Mar-Jun(-Dec). Disturbed sites, lawns, roadsides; 0-600 m; introduced; B.C.; Ala., Ark., Calif., Fla., Ga., La., Miss., N.C., Okla., Oreg., S.C., Tex., Va., Wash.; South America; introduced also in Europe.