Leaves: basal 20-50 × 10-25 cm, blades pinnately compound to pinnatifid (basal leaflets or lobes often pinnatifid); proximal and mid cauline blades 5-9-lobed; adaxial faces glabrous or sparsely hairy (hairs arching, 1-seriate). Receptacles ovoid; paleae 4.5-6.5 mm. Ray laminae 25-50 × 7-12 mm. Discs (17-)20-30 × 12-20 mm. Cypselae 4-5.5 mm; pappi mostly longer than 0.7 mm. 2n = 38. Flowering summer-fall. Wet sites, along streams, open meadows; 1700-2700 m; B.C.; Ariz., Colo., Mont., N.Mex., S.Dak., Wyo. Variety ampla grows west of the Great Plains. It is introduced in British Columbia.