Annuals (sometimes persisting), (10-)30-100+ cm. Leaves: petioles 5-20(-30+) mm; blades ± deltate to ovate or lanceolate overall, 30-100 × 10-50+ mm, usually laciniately 1-pinnatisect, ultimate lobes 3(-7), ovate or lanceolate to linear, (5-)25-60(-70+) × (1-)5-10(-12+) mm, bases cuneate, ultimate margins serrate or entire, often ciliolate, apices acute to attenuate, faces glabrous or hirtellous. Heads usually in open, ± corymbiform arrays. Peduncles 20-120 mm. Calyculi of 7-10 spreading, spatulate to linear, seldom foliaceous (± fleshy) bractlets 5-10 mm, margins usually ciliate, abaxial faces glabrous or hirtellous. Involucres hemispheric or broader, 5-6 × 5-8 mm. Phyllaries (6-)8+, lance-ovate to lanceolate, 4-5 mm. Ray florets 8-13; laminae golden yellow, 12-25+ mm. Disc florets 25-50+; corollas yellowish, 2.5-3 mm. Cypselae blackish or brown, flattened or unequally (3-)4-angled, broadly cuneate, outer 2.5-4, inner 3.5-5 mm (lengths mostly 1.5-2.5 times widths), margins not barbed or ciliate, apices ± truncate, faces sometimes obscurely 1-nerved, sometimes tuberculate, glabrous or hirtellous; pappi 0, or of 2 erect, antrorsely barbed awns or ± deltate scales 0.5(-1) mm. 2n = 24. Flowering Sep-Nov. Marshes, borders of estuaries; 0-100(-300) m; Ala., Ark., Del., Fla., Ga., La., Md., Miss., Mo., N.J., N.C., S.C., Tenn., Tex., Va.
Annual 3-10 dm, glabrous or nearly so; lvs 4-12 cm including the 0.3-3 cm petiole, highly variable in form, pinnately compound to more often pinnately 3-7-parted with the terminal segment the largest, varying to simple, ovate, and merely toothed, or even narrow and subentire; heads rather small, the disk ca 1 cm wide or less; outer invol bracts 7-10, linear or linear-spatulate, 5-10 mm, mostly short-ciliate, glabrous on the back, or the invol sparsely hispid at base; rays ca 8, yellow, 1-2 cm; achenes rather broadly cuneate, 2.5-4.5(-5) mm, glabrous or nearly so, scarcely ciliate; pappus of 2 sharp, antrorsely barbed teeth to 1 mm, or obsolete; 2n=24. Swamps and other wet places; coastal plain from Md. to Fla. and Tex. July-Oct. (B. coronata, misapplied)
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.