Bulbs 2–10+, not clustered on stout, primary rhizome, ovoid, 1–2 × 0.8–1.5 cm; outer coats enclosing 1 or more bulbs, brownish, membranous, with or without obscure reticulations, cells isodiametric or transversely elongate, ± contorted, without fibers; inner coats white, pink, or red, cells obscure, ± quadrate. Leaves usually deciduous with scape, green at anthesis, 2, basally sheathing, sheaths not extending much above soil surface; blade solid, flat to ± terete, channeled, 7–25 cm × 1–4 mm, margins entire or minutely denticulate. Scape usually forming abcission layer and deciduous with leaves after seeds mature, frequently breaking at this level after pressing, solitary, erect, solid, slightly flattened, with or without narrow, sometimes crenulate-denticulate wings, 5–12 cm × 1–2 mm. Umbel persistent, erect, compact, 5–25-flowered, hemispheric, bulbils unknown; spathe bracts persistent, 2–3, 8–11-veined, ovate, ± equal, apex obtuse to acuminate. Flowers campanulate, 6–9 mm; tepals erect, bright pink fading to white with dark midribs, rarely white, oblong to lanceolate, ± equal, becoming papery in fruit, margins obscurely to distinctly serrulate-denticulate, apex obtuse to acuminate; stamens included; anthers yellow; pollen yellow; ovary crestless; style included, linear; stigma capitate, scarcely thickened, unlobed; pedicel 3–10 mm. Seed coat shining; cells smooth. 2n = 14.

Flowering Apr--May. Coarse, sandy soil and gravelly river benches; 800--1100 m; Idaho.

Allium aaseae is known only from Ada and southern Gem counties and Rebecca Sand Hill, Washington County, and is considered of conservation concern by the Idaho Department of Fish and Game.