Rhodora 59: 131. 1957.
Annuals, 10–100 cm. Stems 1–3 (–15), usually branched distally, not winged, glabrous or sparsely hairy. Leaves glabrous or sparsely hairy; basal blades linear to ovate, entire or pinnately toothed or lobed to pinnatifid; mid and distal blades linear, entire. Heads (1–) 10–150 (–250+) per plant, in paniculiform arrays. Peduncles 3–11 cm, sparsely hairy. Involucres hemispheric to globose or globoid, 5–9 × 6–10 mm. Phyllaries moderately to densely hairy. Ray-florets 8–10, pistillate, fertile; corollas yellow, 4.5–14 × 2–10 mm. Disc-florets 75–250+; corollas yellow proximally, yellow to yellowbrown or purple distally, 1.6–2.7 × 0.8–1.2 mm, lobes 5. Cypselae 0.7–1.3 mm, moderately to densely hairy; pappi of 6–8 entire, aristate scales 1–1.8 mm.
Ala., Ark., Calif., D.C., Fla., Ga., Ind., Kans., La., Mich., Miss., Mo., N.C., Okla., Pa., S.C., Tenn., Tex., Va., n Mexico
Varieties 2 (2 in the flora).
|1||Basal and proximal cauline leaves usually withered by flowering; basal blades usually entire or pinnately toothed, sometimes pinnatifid; proximal blades usually entire, sometimes pinnately toothed; disc corollas yellow to yellow-brown distally||Helenium amarum var. amarum|
|1||Basal and proximal cauline leaves often present at, sometimes withered by, flowering; basal blades pinnatifid; proximal blades entire or pinnately toothed or lobed to pinnatifid; disc corollas purple distally||Helenium amarum var. badium|