Robinson's Onion

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.

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.

Oreg., Wash.

Flowering Apr--May.

Sand and gravel deposits along bottom and lower benches of Columbia River; 50--200m.

Allium robinsonii, the Columbia River onion or Robinson's onion, is a rare plant species native to the US States of Washington and Oregon, although some studies suggest that the Oregon populations may now be extinct. The species has been reported from five counties in Washington (Ferry, Yakima, Grant, Franklin and Benton) and five in Oregon (Umatilla, Morrow, Gilliam, Sherman and Wasco). It is found in sand and gravel deposits along the lower Columbia River and some of its tributaries, usually at elevations less than 200 m. The species is also cultivated as an ornamental in other regions, including in Europe.

Allium robinsonii produces 1–3 egg-shaped bulbs up to 2 cm long, but no underground rhizomes. The flowering stalks are relatively short for the genus, rarely more than 8 cm tall. The flowers are bell-shaped, up to 9 mm across; tepals are white to pale pink with red midrib; anthers purple; pollen yellow or gray; ovary crested. The plant is named in honor of B. L. Robinson of the Gray Herbarium of Harvard University. The leaves are flat and succulent, remaining during flowering.