Subshrubs, spreading to some-what sprawling, not scapose, (1.5-)2-4 × 2-5 dm, glabrous, grayish. Stems decumbent to spreading, without persistent leaf bases, up to 1/4 height of plant; caudex stems absent or slightly spreading in moving sand; aerial flowering stems spreading, slender, solid, not fistulose, 0.5-1.5 dm, glabrous.  Leaves basal or sheathing up proximal 1/ 4 of flowering stems, 1 per node; petiole 0.1-0.5(-1) cm, tomentose to floccose; blade broadly elliptic, 1-2(-2.5) × 0.8-1.7 cm, densely white-tomentose abaxially, less so to subglabrous and green adaxially, margins plane. Inflorescences cymose, open, 5-20 × 5-20 cm; branches dichotomous, glabrous; bracts 3, scalelike, triangular, 1-2.5 mm. Peduncles absent or erect, restricted to proximal nodes, (0.2-)0.5-1(-1.5) cm, glabrous. Involucres 1 per node, turbinate, (2.5-)3-3.5 × 2-2.5 mm, glabrous; teeth 5, erect, 0.4-0.8 mm. Flowers 2-3 mm; perianth white, glabrous; tepals connate proximal 1/ 4, essentially monomorphic, narrowly obovate; stamens slightly exserted, 2.5-3.5 mm; filaments puberulent proximally. Achenes light brown, 3-3.5 mm, glabrous except for distinctly papillate beak.

Flowering Jun-Sep. Sandy flats and washes, mixed grassland and sagebrush communities, pinyon-juniper woodlands; of conservation concern; 1600-1900 m; Utah.

Eriogonum ammophilum is known only from a few, scattered locations in Millard County. It is considered to be a 'sensitive' species by the Bureau of Land Management.