Plants herbs, spreading, not scapose, 2–5 (6) dm tall, 2–5 dm across, glabrous, green; stems spreading, without persistent leaf bases, up to 1/5 height of plant, the caudex stems spreading, glabrous, the aerial flowering stems erect, slender, solid, not fistulose, 1.2–3 dm long, glabrous, tomentose among leaves; leaves basal or sheathing up stem less than 2 cm, 1 per node, the petioles (0.1) 3–7 (10) cm long, tomentose to floccose or glabrous, the blades linear or oblong to oblanceolate or elliptic, 2–8 (10) cm long, 0.2–2.5 (3) cm wide, thinly to densely white-tomentose abaxially, glabrous and green adaxially, the margins plane or slightly revolute; inflorescences cymose, open, 10–30 cm long, 10–25 cm wide, the branches dichotomous, glabrous, the bracts 3, scalelike, linear, 2–5 (7) mm long; peduncles absent; involucres 1 per node, turbinate, 2–3 (3.5) mm long, 1–1.5 (2) mm wide, glabrous, the teeth 5, erect, 0.4–0.5 mm long; flowers 3–3.5 mm long, the perianth yellow or white, glabrous, the hypanthium up to 1⁄2 length of perianth, the tepals monomorphic, oblong to obovate, the stamens slightly exserted, 3–3.5 (4) mm long, the filaments sparsely pilose proximally; achenes light brown to brown, 2.5–3 mm long, glabrous except for slightly papillate beaks.
- Leaf blades linear, 3–8 (10) long, 0.2–0.4 (0.6) cm wide : Eriogonum thompsoniae var. atwoodii.
- Leaf blades oblong to oblanceolate or elliptic; 2–5 cm long 0.8–2.5 (3) cm wide.
- Perianth yellow : Eriogonum thompsoniae var. thompsoniae.
- Perianth white : Eriogonum thompsoniae var. albiflorum.
Plants 2–5 (6) dm tall; leaf blades oblong to oblanceolate or elliptic, 2–5 cm long, 0.8–2.5 cm wide, tomentose abaxially, the margins plane; involucres 2–3 mm long, the perianth white. – NOTE: The var. matthewsiae phase may represent a hybrid between var. albiflorum and E. corymbosum.
Flowering Jun-Oct. Sandy to gravelly, often volcanic flats and slopes, saltbush and blackbrush communities, pinyon-juniper and oak woodlands; 900–1400 m; southern Washington Co., Utah, and adjacent northern Mohave Co., Arizona.