Bulbs 1–3(–5), not clustered on stout primary rhizome, ovoid, 1–2 × 1–2 cm; outer coats enclosing 1 or more bulbs, brown, prominently cellular-reticulate, membranous, accumulating and investing bulb with thick cover, cells square, polygonal, or ± transversely elongate, walls thick, sinuous, without fibers; inner coats white to light brown, cells ± obscure, quadrate. Leaves persistent, withering from tip at anthesis, 2–3, basally sheathing, sheaths not extending much above soil surface; blade solid, flattened, subterete or ± channeled and carinate, ± falcate, 10–30 cm × 0.5–3 mm, margins entire. Scape persistent, solitary, erect, solid, terete, 10–35 cm × 1–4 mm. Umbel persistent, erect, compact or loose, 5–45-flowered, bulbils unknown, umbel shattering after seeds mature, each flower deciduous with its pedicel; spathe bracts persistent, 2–3, 4–6-veined, lance-ovate to ovate, ± equal, apex obtuse or acuminate. Flowers campanulate, 4–9 mm; tepals erect or spreading from base, white to deep pink with darker midveins, lance-ovate to ovate, ± equal, margins entire, apex obtuse, acute, or short-acuminate; stamens included; anthers yellow; pollen yellow; ovary 3-grooved with ridge on either side of each groove, ridges prolonged into crest, ridges and crest densely covered with minute, rounded papillae; processes 3, central, 2-lobed, minute; style linear, equaling stamens; stigma capitate, scarcely thickened, obscurely 3-lobed; pedicel 4–30 mm. Seed coat dull or shining; cells minutely roughened.
Varieties 4 (4 in the flora).
|1||Umbel compact; pedicel 0.75–1.5 times flower; scape 10–25 cm.||> 2|
|1||Umbel loose; pedicel equaling–3.5 times flower; scape 15–35 cm.||> 3|
|2||Scape 10–20 cm; leaf blade 1–2 times scape; flowers (6–)7–9 mm; Coast Ranges of c California and Channel Islands.||Allium lacunosum var. lacunosum|
|2||Scape 15–25 cm; leaf blade equaling or shorter than scape; flowers 6–7(–8) mm; Sierra Nevada, California.||Allium lacunosum var. kernensis|
|3||Leaf blade subterete, 1 mm or less wide, straight; spathe bracts 3, apex obtuse or acute; flowers 4–6 mm.||Allium lacunosum var. micranthum|
|3||Leaf blade ± carinate, to 3 mm wide, ± falcate; spathe bracts 2, apex acuminate; flowers 6–8 mm.||Allium lacunosum var. davisiae|