General:
Perennial herb from a woody stem-base surmounting a taproot; stems 1 to many, erect, 5-25 (35) cm tall; more or less greyish long-hairy throughout.

Leaves:
Basal, (3) 5 to 8 (10), ascending, 4-10 cm wide, mostly 3-parted with each leaflet dichotomously dissected, the ultimate segments linear, 1-3 mm wide, soft-hairy, rarely smooth; stalks 5-10 cm long.

Flowers:
Inflorescence a solitary, terminal flower; flower stalks soft-hairy, sometimes becoming smooth in age; involucral bracts mostly 3, leaf-like but differing from basal leaves, simple, unstalked, bases clasping and joined, margins deeply incised throughout, segments usually 4 to 6, long and slender or linear, not lobed, generally soft-hairy, rarely smooth; petals absent; sepals 5 to 8, petal-like, blue or purple, rarely nearly white, oblong to elliptic, 20-40 mm long, 10-15 mm wide, hairy outside, smooth inside; stamens 150-200.

Fruits:
Achenes, numerous in a spheric to egg-shaped head on stalks 10-18 cm long, the achenes ellipsoid to egg-shaped, 3-4 mm long, about 1 mm wide, not winged, soft-hairy; beaks (styles) curved, 2-4 cm long, short-feathery-hairy.

Notes:
The Eurasian material (ssp. patens) appears to be scarcely distinguishable from the North American plants.

Source:  The Illustrated Flora of British Columbia