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).
FNA 2006, Kearney and Peebles 1969, McDougall 1973
Duration: Perennial Nativity: Native Lifeform: Forb/Herb General: Herbaceous perennials simply branching, stems to 40 cm tall, often curved at the base, hirsute or glabrate below, minutely glandular to stipitate glandular, with fibrous roots and a woody caudex. Leaves: Alternate, basal leaves oblanceolate, obovate, or oval, to 5 cm long, narrowing to a petiole, glabrate to ciliate, cauline leaves smaller and often sessile. Flowers: Heads small, radiate, the rays blue, rarely pink or white, 75-150, 7-15 mm long, coiling or not, the disk yellow, 15-18 mm wide, the involucre 5-8 mm high, the phyllaries equal, in 2-3 series, glabrous to somewhat villous, minutely to noticeably stipitate glandular, inflorescences solitary or few on each stem. Fruits: Achenes 2 nerved, hairy. Pappus sparse, of subequal capillary bristles, the inner of 15-25 long bristles, the outer of short, stiff bristles. Ecology: Found in coniferous forests from 5,500-10,500 ft (1676-3200m); flowering July-September. Distribution: Western South Dakota, Wyoming, and Utah, to New Mexico and Arizona. Ethnobotany: Taken as an infusion or lotion for good luck in hunting. Etymology: Erigeron means Early-Old-Man, as named by Theophrastus, while formosissimus means very handsome or beautiful. Synonyms: Erigeron formosissimus var. formosissimus, Erigeron formosissimus var. typicus, Erigeron formosissimus var. viscidus, Erigeron glabellus var. viscidus, Erigeron viscidus Editor: SBuckley, 2010, LCrumbacher