General: Perennial herb from a compact, multibranched stem-base; stems ascending, simple, leafless, sparsely to densely glandular-hairy and stiff-hairy with long, spreading, white hairs, often densely woolly below the heads, 3-10 cm tall.
Leaves: Basal leaves 0.8-3.0 cm long, mostly three-lobed, rarely two-lobed or occasionally entire, the basal segments about 1-2 mm wide, the sides tapering to the base, the lobes 3-8 mm long, generally lanceolate to narrowly egg-shaped or oblong, the central lobes dilated at the tips, abruptly sharp-pointed, coarsely fringed with small hairs, sparsely to densely stiff-hairy above and below and sparsely glandular as well; stem leaves lacking.
Flowers: Heads with ray and disk flowers, solitary; involucres 8-12 mm tall; involucral bracts sparsely to densely, glandular stiff-hairy, narrowly lanceolate, tapering to a slender tip, purple or purplish-tipped; ray flowers 20-40, white or sometimes pink, 10-15 mm long; disk flowers 3.5-4.5 mm long.
Fruits: Achenes 2-nerved, densely hairy; pappus simple, of 15-20 bristles.
Three-lobed daisy (Asteraceae) is a rare red-listed and narrowly distributed plant known only from high alpine areas along the spine of the Canadian Rocky Mountains in British Columbia and Alberta. After reviewing the herbarium specimens identified as E. trifidus housed at the UBC herbarium it became apparent that even expert botanists are confusing this rare species with another high alpine, but widely distributed species called Erigeron compositus Pursh (cut-leaved daisy). However, these two species can easily be told apart based on their leaves alone. Erigeron trifidus is aptly named because the species epithet “trifidus” is a Latin word meaning “three lobed”, and the tips of the leaves of this species are indeed divided into three lobed only. The leaves of E. compositus at first glance may seem similar but upon closer inspection the tips of the leaves have more than three lobes, and there are often multiples sets of three lobes. The key in Flora of North America (volume 20. p. 265) uses the term 2-3 times ternateley lobed, which is just a fancy way of saying that the leaves are dissected into two to three set of three lobes (i.e. they have six to nine lobes).
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)
