Annuals or short-lived perennials, 30-70 cm; taprooted. Stems erect, coarsely hirsute to hispid (hairs only along ribs, bases thickened), minutely glandular. Leaves mostly cauline; blades linear to linear-oblong, -lanceolate, or -oblanceolate (slightly narrowed distally), 25-50 × 2-5 mm, margins entire or sometimes lobed (lobes 1-2 pairs, coarse, rounded), faces hispido-strigose. Heads 20-50+ in loose, corymbiform arrays (buds erect). Involucres 2.5-3.5 × 5-8 mm. Phyllaries in 3-4 series, minutely hispid, minutely glandular. Ray florets 125-180; corollas usually white, sometimes lavender or pinkish, 6-7 mm, laminae reflexing. Disc corollas 2-2.5 mm (throats indurate and inflated). Cypselae 0.7-1 mm, 2-nerved (nerves orange), faces sparsely strigose to glabrate; pappi: outer of setae or lanceolate scales, inner of (10-)12-17 bristles. 2n = 18.

Flowering May-Jun(-Nov). Grasslands, often in moist areas, sometimes with mesquite, openings, roadsides, oak, juniper, mesquite; of conservation concern; (800-)1300-1700 m; Ariz.; Mexico (Sonora).

Erigeron arisolius is similar in general appearance to E. divergens; the erect buds and reflexing rays of E. arisolius contrast with the nodding buds and non-reflexing rays of E. divergens. Additionally, the latter has evenly distributed stem pubescence, cypselae with whitish nerves (versus orange), and fewer pappus bristles. Erigeron sceptrifer also may be difficult to distinguish from these: it is more similar to E. arisolius in vestiture and has shorter rays that usually become purple upon drying and that are downward-curved, compared to those of E. arisolius, where the rays dry a lighter color and reflex at the tube-lamina junction.

FNA 2006, Wiggins 1964, Kearney and Peebles 1969

Duration: Annual Nativity: Native Lifeform: Forb/Herb General: Annual or short-lived perennial, 3-70 cm, taproot. Erect stems, coarsely hirsute to hispid (hairs only along ribs, bases thickened), minutely glandular. Leaves: Mostly cauline, blades linear to linear-oblong, lanceolate to oblanceolate, 25-50 mm long by 2-5 mm wide, margins entire or sometimes lobed (lobes 1-2 pairs, coarse, rounded). Flowers: Heads 20-50+ in loose, corymbiform arrays (erect buds); involucres 2.5-3.5 mm by 5-8 mm, phyllaries in 3-4 series, minutely hispid, minutely glandular; ray flowers 125-180; corollas white, sometimes lavender or pinkish, 6-7 mm, laminae reflexing; disc corollas 2-25 mm (throats indurate and inflated); flowers May-June. Fruits: Cypselae (achene with adnate calyx) 0.7-1 mm, 2-nerved (nerves orange), faces sparsely strigose to glabrate, pappus 12-17 bristles. Ecology: Grasslands, often in moist areas, sometimes with mesquite, in openings, roadsides, oak; 4,000-5,500 ft (1219-1676 m) Notes: Of conservation concern. Similar in appearance to E. divergens; the erect buds and reflexing rays of E. arisolius contrast with the nodding buds and non-reflexing rays of E. divergens. E. divergens also has evenly distributed stem pubescence. Ethnobotany: Unknown for this species, other species in this genera have many uses. Etymology: Erigeron means Early-Old-Man, as named by Theophrastus, while arisolius means dry sun.  Editor: SBuckley, 2010