Dwarf Onion - Allium simillimum
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.
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 et al. 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX
Flowering in June-July.
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.
Central and southwest ID, southwest MT. Regional endemic.
Observations in Montana Natural Heritage Program Database
Number of Observations:
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Map Help and Descriptions
(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.
The following animal species have been reported as pollinators of this plant species or its genus where their geographic ranges overlap: Bombus bifarius
, Bombus centralis
, Bombus flavifrons
, Bombus huntii
, Bombus melanopygus
, Bombus sylvicola
, Bombus occidentalis
, and Bombus bohemicus
(Macior 1974, Thorp et al. 1983, Colla and Dumesh 2010, Koch et al. 2012, Miller-Struttmann and Galen 2014, Williams et al. 2014).
Threats or Limiting Factors
STATE THREAT SCORE REASON
Threat impact not assigned because threats are not known (MTNHP Threat Assessment 2021).
- Literature Cited AboveLegend: View Online Publication
- Colla, S.R. and S. Dumesh. 2010. The bumble bees of southern Ontario: notes on natural history and distribution. Journal of the Entomological Society of Ontario 141:39-68.
- Koch, J., J. Strange, and P. Williams. 2012. Bumble bees of the western United States. Washington, DC: USDA Forest Service, Pollinator Partnership. 143 p.
- Lesica, P., M.T. Lavin, and P.F. Stickney. 2012. Manual of Montana Vascular Plants. Fort Worth, TX: BRIT Press. viii + 771 p.
- Macior, L.M. 1974. Pollination ecology of the Front Range of the Colorado Rocky Mountains. Melanderia 15: 1-59.
- Miller-Struttmann, N.E. and C. Galen. 2014. High-altitude multi-taskers: bumble bee food plant use broadens along an altitudinal productivity gradient. Oecologia 176:1033-1045.
- Thorp, R.W., D.S. Horning, and L.L. Dunning. 1983. Bumble bees and cuckoo bumble bees of California (Hymenoptera: Apidae). Bulletin of the California Insect Survey 23:1-79.
- Williams, P., R. Thorp, L. Richardson, and S. Colla. 2014. Bumble Bees of North America. Princeton, NJ: Princeton University Press. 208 p.