Annuals (biennials), 30-100+ cm. Leaves: petioles 5-30 mm; blades ± deltate to ovate overall, 40-80(-150+) × 25-50(-80+) mm, usually laciniately 1-pinnatisect, ultimate lobes 3(-7), lanceolate to linear, 25-60(-120+) × (3-)6-20(-25) mm, bases cuneate, ultimate margins incised, dentate, or serrate, ciliate, apices acute to attenuate, faces glabrous or hirtellous to scabrellous. Heads borne singly or in 2s or 3s or in open, ± corymbiform arrays. Peduncles 10-20(-50) mm. Calyculi of 12-21+ spreading to reflexed, linear, seldom foliaceous bractlets (6-)8-12(-20+) mm, margins coarsely ciliate, abaxial faces glabrous or scabrellous. Involucres turbinate to hemispheric, 4-5 × 6-10 mm. Phyllaries 6-8+, lance-ovate to lanceolate, 4-7 mm. Ray florets 8; laminae golden yellow, 10-25+ mm. Disc florets (40-)60-100+; corollas yellow, 2.5-3 mm. Cypselae blackish or brown to yellowish, ± flattened, obovate or oblanceolate to cuneate, outer 5-7 mm, inner 7-8 mm (lengths mostly 1.5-2.5 widths), margins (± corky-winged) antrorsely barbed or ciliate, apices ± truncate, faces glabrous or strigillose, sometimes tuberculate; pappi 0, or of 2 divergent, retrorsely barbed awns or ± deltate scales 0.1-0.5(-1.5) mm. 2n = 24. Flowering Aug-Oct. Marshes, bogs, flood plains, disturbed sites; 10-1500 m; Ont.; Ala., Ark., Colo., Ill., Ind., Iowa, Kans., La., Md., Mich., Mo., Nebr., N.J., N.Mex., N.C., Okla., Pa., S.C., Tenn., Tex., Va.