Annuals, 30-200 cm. Stems glabrous. Leaves: proximal usually persistent at flowering, cauline blades obscurely (1-), 3-, or 5-nerved, mostly narrowly elliptic-lanceolate, 40-70 × 2-4 mm, reduced distally. Heads usually in open arrays. Involucres campanulate, 4.5-7.5 mm diam. Phyllary apices conduplicate, swollen (appearing abaxially keeled). Ray florets 8-19; corollas yellow, 5-12 mm. Disc florets (30-)40-60. Cypselae 0.7-2 mm, faces (pebbly or warty with raised, blisterlike oil cavities) glabrous; pappi coroniform, 0.1-0.2 mm (margins entire or obscurely denticulate or erose). 2n = 8. Flowering Jul-Oct(-Nov). Meadows and clearings in pine, pine-oak, and pine-fir woods, ditches, road cuts, alluvium; 1800-2800 m; Ariz., N.Mex.; Mexico (Chihuahua, Sinaloa, Sonora).