Sp. Pl. 2: 886. 1753.
Perennials, 50–130 cm. Stems 1 (–7), branched distally, strongly winged, sparsely to densely hairy proximally, moderately to densely hairy distally. Leaves usually moderately to densely hairy, sometimes glabrous; basal blades (withered by flowering) lanceolate, oblanceolate, or obovate, entire or weakly lobed; proximal and mid-blades obovate to oblanceolate, usually dentate or entire; distal blades oblanceolate to lanceolate, entire or dentate. Heads 5–70 (–100+) per plant, in paniculiform arrays. Peduncles 3–10 cm, moderately to densely hairy. Involucres globoid, 8–20 × 8–23 mm. Phyllaries (connate proximally) moderately to densely hairy. Ray-florets 8–21, pistillate, fertile; corollas yellow, 10–23 × 4–10 mm. Disc-florets 200–400 (–800+); corollas yellow proximally, yellow to yellowbrown distally, 2.4–4 mm, lobes 5. Cypselae 1–2 mm, sparsely to moderately hairy; pappi of 5–7 entire, aristate scales (0.5–) 0.9–1.5 (–1.8) mm. 2n = 32, 34, 36.
Phenology: Flowering (Jul–)Aug–Oct(–Nov).
Habitat: Roadsides, fields, along streams, ditches, seepage areas, around ponds and lakes
Elevation: 20–2600 m
Alta., B.C., Man., N.W.T., Ont., Que., Sask., Ala., Ariz., Ark., Calif., Colo., Del., D.C., Fla., Ga., Idaho, Ill., Ind., Iowa, Kans., Ky., La., Md., Mass., Mich., Miss., Mo., Mont., Nebr., Nev., N.J., N.Mex., N.Y., N.C., N.Dak., Ohio, Okla., Oreg., Pa., S.C., Tenn., Tex., Utah, Va., Wash., W.Va., Wyo.