Perennials, 10-40(-55) cm; rhizomatous, fibrous-rooted, rhizomes variably thick. Stems ascending, densely hirsute to hirsutulous or glabrous, minutely glandular to stipitate-glandular. Leaves basal (persistent) and cauline; basal blades oblanceolate to oblanceolate-spatulate, 20-100(-150) × 4-10(-15) mm, margins entire, closely ciliate, faces glabrous or sparsely hirsute, sometimes sparsely glandular; cauline blades becoming ovate to lanceolate, gradually reduced distally (bases clasping). Heads 1-6. Involucres 5-8 × 10-20 mm. Phyllaries in 2-3 series (greenish), glabrous or hirsuto-villous, densely minutely glandular to stipitate-glandular (glands sometimes obscured by hairs in var. formosissimus). Ray florets 75-150; corollas blue to purple, rarely pink to white, 8-15 mm (ca. 1 mm wide), laminae coiling at tips or not at all. Disc corollas 3.5-4.5 mm. Cypselae (1.3-)1.6-1.9 mm, 2-nerved, faces sparsely strigose; pappi: outer of setae, inner of 15-25 bristles. Variation in vestiture of Erigeron formosissimus is complex, ranging from stems and heads glabrous and densely stipitate-glandular to stems and heads densely hairy and essentially eglandular; intermediates are found over the range of the species. The taxonomic solution of recognizing broadly sympatric varieties within a single species is biologically untenable, and some have treated this as a single entity; the variation is greater than typically occurs within a single species of Erigeron (see comments following 3. E. neomexicanus, where the situation with E. oreophilus is similar).