General:
Perennial, aromatic herb, usually rhizomatous; stems erect, slender, 10-100 cm tall.

Leaves:
Fernlike, alternate, stalked below and unstalked above, pinnately dissected, the divisions again dissected.

Flowers:
Heads numerous, in a short, flat or round-topped cluster; involucral bracts dry, overlapping in several series, often dark-margined; ray flowers usually 3-8, 2-3.5 mm long, white to sometimes pink or reddish; disk flowers 15-40, cream colored.

Fruits:
Achenes glabrous, flattened, 1-2 mm long; pappus lacking.

Notes:
Taxonomically, one of our most complex species. Tyrl (1980) presented a sound case for recognizing only a single variable species. I, however, have recognized four, broad ecogeographical forms (sensu Nobs 1960) at the varietal level since these forms are ecologically significant in BC.

1. Leaves grey, long-hairy to woolly; plants usually in and east of the Coast-Cascade Mountains.

2. Involucral bract margins light brown to black; stems usually less than 30 cm tall; plants of the subalpine and alpine zones................. var. alpicola (Rydb.) Garrett

2. Involucral bract margins light brown to straw-coloured; stems usually more than 30 cm tall; plants of the montane and steppe zones........................ var. lanulosa (Nutt.) Piper in Piper & Beattie

1. Leaves usually green, moderately long-hairy; plants of coastal regions.

3. Involucral bract margins dark brown to black; stems 10-40 cm tall........................ var. borealis (Bong.) Farwell

3. Involucral bract margins hyaline to light straw-coloured; stems 30-100 cm tall.................. var. pacifica (Rydb.) G.N. Jones

Source:  The Illustrated Flora of British Columbia