Perennials, (1.5-)5-25(-30) cm; rhizomatous, fibrous-rooted, forming diffuse systems of slender, rhizomelike caudex branches. Stems ascending (bases usually purplish), glabrous or sparsely strigose (or hairs loosely spreading), sometimes glandular near heads. Leaves basal (persistent) and cauline; basal (purplish) and proximal blades narrowly oblanceolate to oblong, 20-120 × 2-11 mm, cauline reduced distally, margins entire, ciliate, faces glabrous or loosely strigose, eglandular. Heads 1(-3). Involucres 5-7 × 9-19 mm. Phyllaries in 2-3(-4) series (margins and tips often purplish, loose, linear-lanceolate, apices spreading), sparsely to moderately villous to hirsuto-villous, densely minutely glandular. Ray florets 30-100; corollas pink to bluish purple, 6-15 mm, laminae not reflexing or coiling, sometimes tardily coiling. Disc corollas 3.2-4.7 mm. Cypselae 1.5-2 mm, 2-nerved, faces sparsely strigose; pappi: outer of setae, inner of 10-20 bristles. 2n = 18. Flowering Jul-Sep. Meadows and grassy openings, sagebrush, aspen, lodgepole pine, pine-fir, spruce-fir; 2400-3100(-3700) m; Ariz., Colo., Idaho, Mont., Nev., N.Mex., Utah, Wyo.
General: Perennial, 5-25 cm tall; stems ascending, purplish at base, glabrous to sparsely strigose, sometimes glandular below the heads; caudex branched, many rhizome-like; fibrous-rooted. Leaves: Basal (persistent) and cauline, alternate, the basal (purplish) and lower cauline leaves oblanceolate to oblong, 2-12 cm long, 2-11 mm wide, the cauline leaves linear to lanceolate, reduced upwards, surfaces glabrous or sparsely strigose, margins entire, ciliate; basal leaves petiolate, cauline leaves sessile or nearly so. Flowers: Heads solitary or few; involucre 3.5-4.5 mm long, 6-9 mm wide; phyllaries in 3-4 series, sparsely to moderately hirsute, minutely glandular; ray flowers 75-190, 5-10 mm long, blue, pink, or white; disk flowers numerous, 2-3 mm long, yellow; flowers May-August. Fruits: Achene, 1.5-2 mm long, sparsely strigose, 2-veined; pappus in 2 series, the inner of 10-20 bristles, outer of short bristle-like scales. Ecology: Meadows, grassy openings, forested slopes; 2400-3700 m (8000-12000 ft); Coconino County; southwestern U.S. Notes: Erigeron ursinus bears some similarity to E. formosissimus, but E. ursinus is sparsely strigose and not as robust as E. formosissimus. Erigeron rhizomatus (rhizome fleabane) is 25-45 cm tall; stems are erect, simple or branched, sparsely strigose to strigose- hirsute; rhizomes or rhizome-like caudex branches are creeping, scale-leaved; leaves are cauline, 1-3 mm wide; corollas of the ray flowers are white with lilac midstripe on underside; achenes are 3.5-4.5 mm long, 5-6 veined, glabrous. This rare species is found in ponderosa pine forests and pinyon-juniper woodlands of Apache County, and is restricted to specific shale substrates. Editor: Springer et al. 2008