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Montana Field Guide

Montana Field Guides

Dwarf Onion - Allium simillimum

Species of Concern
Native Species

Global Rank: G4
State Rank: S2?
(see State Rank Reason below)

Agency Status
MNPS Threat Rank:

External Links

State Rank Reason (see State Rank above)
Rare in Montana, where it is known from only a few locations in the southwest portion of the state near the Idaho border. Available survey data are limited for the species in Montana.
General Description
Bulbs ovoid, usually solitary; outer coat membranous with hexagonal reticulations. Scapes slightly flattened, partly subterranean, 2–6 cm. Leaves 2, channeled, ca. 1 mm wide, persistent. Umbel compact, campanulate to hemispheric with 5 to 15 flowers; pedicels 2–5 mm long; bracts 2, ovate, apiculate. Flowers: tepals white with green to purple midveins, 6–8 mm long; ovary with 3 crests adjacent to the style; stamens included. Seed surface smooth (Lesica 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).

Flowering in June-July.

Diagnostic Characteristics
Allium parvum is similar but has a strongly flattened stem. Allium brandegeei is also similar but has leaves that are less than twice the length of the stem.

Species Range

Range Comments
Central and southwest ID, southwest MT. Regional endemic.

Observations in Montana Natural Heritage Program Database
Number of Observations: 18

(Click on the following maps and charts to see full sized version) Map Help and Descriptions
Relative Density



(Observations spanning multiple months or years are excluded from time charts)

Moist, often gravelly soil of meadows and grasslands in the montane or lower subalpine zone.

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Citation for data on this website:
Dwarf Onion — Allium simillimum.  Montana Field Guide.  .  Retrieved on , from