Plants (10-)70-150 cm. Stems usually simple, often with short, leafy branches proximally. Heads 20-100, in open, diffuse arrays, primary branches longer than peduncles. Involucres 5-6.2 mm. Phyllaries 30-42, sub-ulate to lanceolate, narrow, green zones narrowly lanceolate. Ray florets (23-)27-37(-42) in (1-)2 series; laminae usually white, sometimes pink, 1.9-3 × 0.2-0.5 mm, longer than pappi, drying in 1-2 coils (apices shallowly to deeply lobed). Disc florets (6-)8-15; corollas 3.4-4.4(-4.7) mm. Cypselae 1.5-2.7 mm; pappi 3.5-3.8(-4.2) mm. 2n = 10. Flowering Jul-Nov(-Jan). Roadsides, marshy habitats, often weedy; 0-1100(-4000) m; Ala., Ariz., Calif., Fla., Nev., N.Mex., Okla., Tex., Utah; Mexico; West Indies; Central America; n South America; introduced in Asia (Japan), Pacific Islands (Hawaii).