140. Erigeron arizonicus A. Gray, Proc. Amer. Acad. Arts. 19: 2. 1883.
Erigeron rusbyi A. Gray
Perennials, 8–40(–60) cm; rhizomatous, fibrous-rooted, caudices or rhizomes relatively thick, simple or branched, sometimes resembling a taproot. Stems erect to basally ascending, moderately to densely strigose to strigoso-hirsute or hirsute, eglandular. Leaves basal (commonly persistent) and cauline; basal blades often 3-nerved, spatulate, obovate to ovate, or elliptic, 20–150 × 5–25 mm, margins entire to shallowly serrate, faces loosely strigose, rarely minutely glandular; cauline blades slightly smaller than basal, relatively even-sized to peduncle bases, (bases subclasping) margins entire, becoming lanceolate (bases non-clasping) distally. Heads 1–4(–6) (from branches on distal 1 / 3 – 1 / 2 of stem, peduncles distinct, 1.5–9 cm). Involucres 5–7 × 9–18 mm. Phyllaries in 3–4 series (greenish), moderately piloso-hirsute, densely minutely glandular (sometimes obscured by hairs). Ray florets 25–80; corollas white, drying white or lilac-tinged, 8–10 mm (ca. 1 mm wide), laminae coiling at tips. Disc corollas 2.9–4 mm. Cypselae 1.6–2.1 mm, 2-nerved, faces sparsely strigose; pappi: outer of setae, inner of 15–26 bristles. 2n = 18.
Flowering (May–)Jul–Sep(–Oct). Grassy slopes, openings, roadsides, sometimes rock crevices and ledges, oak-juniper to oak-pine, pine, pine-fir, Douglas fir, spruce-fir; (1800–)2100–2900(–3200) m; Ariz., N.Mex.; Mexico (Sonora).