Rhodora 32: 22. 1930.
Bulbs 1–3+, not clustered on stout primary rhizome, rhizomes absent, renewal bulbs formed within coats of parent bulb, increase bulbs absent or 1–2, ± equaling parent bulbs, never appearing as basal cluster, ovoid, 1–2 cm × 8–15 mm; outer coats grayish to brownish, membranous, lacking cellular reticulation or cells arranged in only 2–3 rows distal to roots, ± quadrate, without fibers; inner coats white, cells absent or ± quadrate. Leaves usually deciduous with scape, 2, basally sheathing, sheaths not extending much above soil surface; blade solid, flat, strongly falcate, 5–18 cm × 1–2 mm, margins entire. Scape usually forming abcission layer and deciduous with leaves after seeds mature, frequently breaking at this level after pressing, solitary, erect, solid, flattened, slightly 2-edged, 3–7 cm × 1–3 mm. Umbel deciduous with scape, erect, compact, 5–12-flowered, hemispheric, bulbils unknown; spathe bracts persistent, 2, 5–8-veined, ovate, ± equal, apex abruptly acute. Flowers campanulate, 7–9 mm; tepals erect, white to pale-pink with red midribs, oblong, ± equal, becoming papery and not carinate in fruit, margins entire, apex obtuse; stamens included; anthers purple; pollen gray or yellow; ovary ± distinctly crested; processes 3 or 6, central, low, rounded, margins entire; style included, linear; stigma capitate, unlobed; pedicel 3–12 mm. Seed-coat dull; cells smooth. 2n = 14.
Phenology: Flowering Apr–May.
Habitat: Sand and gravel deposits along bottom and lower benches of Columbia River
Elevation: 50–200 m
Allium robinsonii has been found along the Columbia River from Ferry County, northeastern Washington, to about the mouth of the John Day River, north-central Oregon, and is now possibly extirpated from Oregon.
"thicker" is not a number."broad" is not a number.