Blue Mountain Onion

Allium dictuon is known only from the vicinity of Weller’s Butte, Blue Mountains. It differs from A. acuminatum by its rhizomatous habit, in which it resembles A. bolanderi, and in the cellular pattern on the inner bulb coats.

Bulbs usually solitary, forming rhizomes; rhizomes 1–2, terminated by 1–3 new bulbs, short, slender; parent bulb disappearing by anthesis except for still-functional roots and bulb coats, not basally clustered, oblique-ovoid, 1–1.5 × 0.9–1.5 cm; outer coats not enclosing bulbs, pale brown, prominently cellular-reticulate, membranous, cells polygonal to oblong, walls thick, obscurely sinuous, without fibers; inner coats white, cells ± transversely elongate, intricately contorted. Leaves persistent, withering from tip by anthesis, 2–3, basally sheathing, sheaths not extending much above soil surface; blade solid, subterete to ± channeled, 10–28 cm × 1–2 mm, margins entire. Scape persistent, solitary, erect, solid, terete, 20–40 cm × 1–3 mm. Umbel persistent, erect, loose, 10–25-flowered, hemispheric, bulbils unknown; spathe bracts persistent, 2, 3-veined, lanceolate to lance-ovate, ± equal, apex acuminate. Flowers campanulate, 11–16 mm; tepals erect, pink to rose-purple, lanceolate, unequal, outer tepal longer and wider than inner, becoming rigid and keeled in fruit, margins finely denticulate (inner tepal more prominently so), apex acute to narrowly obtuse, becoming involute and appearing long-acuminate, flaring toward tips; stamens included; anthers yellow; pollen yellow; ovary crested; processes 3, central, 2-lobed, rounded, minute, margins entire; style linear, equaling stamens; stigma capitate, scarcely thickened, obscurely 3-lobed; pedicel 10–25 mm. Seed coat shining; cells minutely roughened. 2n = 14.

Wash.

Flowering Jun--Jul.

Rocky, sandy, basaltic soil; of conservation concern; 1500m.

Allium dictuon is a species of wild onion known by the common name Blue Mountain onion. It is native to a small section of the Blue Mountains straddling the border between southeastern Washington and northeastern Oregon in the United States. It grows in Columbia, Garfield and Walla Walla Counties in Washington, plus Umatilla and Wallowa Counties in Oregon.

Allium dictuon grows from bulbs connected by rhizomes. It produces two or three leaves each up to 28 centimeters in length. The scape is 20 to 40 centimeters tall and bears an umbel of up to 25 flowers. The bell-shaped flowers are bright pink or purplish and each is 1.1 to 1.6 centimeters long. Blooming occurs in June and July.

Allium dictuon grows in dry, open, rocky habitat. The vegetation in the area is dominated by bluebunch wheatgrass (Pseudoroegneria spicata ssp. spicata).

The total population has been estimated to be between 200 and 500 individuals.