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
Two species of Achillea in BC may be confused: Achillea millefolium and A. sibirica. The third species, A. ptarmica, is distinctive, with few, larger flowerheads.
Key to A. millefolium and A. sibirica:
1. Leaves pinnately dissected, the divisions again dissected; plants widespread in BC......................A. millefolium
1. Leaves incised, the divisions of the latter merely toothed; plants of northeastern BC.......................A. sibirica
Source: Illustrated Flora of British Columbia
Habitat / Range
Mesic to dry coastal bluffs, meadows, grasslands, rocky slopes and open forests in all vegetation zones; common throughout BC; N to AK, YT and NT, E to NF and S to FL, TX, CA, and MX. Description
This species has been observed flowering in the Fraser Delta in December.
Ecology
Ecological Framework for Achillea millefolium
The table below shows the species-specific information calculated from original data (BEC database) provided by the BC Ministry of Forests and Range. (Updated August, 2013)
