21. Erigeron disparipilus Cronquist, Brittonia. 6: 194. 1947.
White cushion fleabane
Perennials, 3–12 cm; taprooted, caudices branched. Stems erect, densely pilose to hirsute or villoso-hirsute (hairs usually slightly ascending, loose, often mixed in orientations, of unequal lengths, relatively thin-based), eglandular. Leaves mostly basal (persistent), (petioles prominently ciliate, hairs thick-based, spreading); blades linear to linear-oblanceolate, 20–40 × 1–2 mm, margins entire, faces finely hirsute, eglandular; cauline reduced, restricted to proximal 1 / 3 of stems. Heads 1. Involucres 5–7 × 8–16 mm. Phyllaries in 2–3 series, hirsute to hirsuto-strigose, minutely glandular. Ray florets mostly 30–60; corollas usually white, sometimes fading pink, rarely blue, 5–10 mm, laminae loosely coiling. Disc corollas 2.8–4 mm. Cypselae 1.8–2.2 mm, 2-nerved, faces moderately, loosely strigose; pappi: outer of setae, inner of 15–25 bristles.
Flowering May–Aug. Gravelly and rocky slopes, ridges, sagebrush, grassland; 600–2000(–2200) m; Idaho, Oreg., Wash.
Erigeron disparipilus is similar to E. nanus but less variable. The range of E. disparipilus barely contacts that of E. nanus in southeastern Idaho and they have different ecologies; blue rays of E. disparipilus in Owyhee County may indicate that hybridization occurs.