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Montana Field Guide

Montana Field Guides

Tapertip Onion - Allium acuminatum

Species of Concern
Native Species

Global Rank: G5
State Rank: S2S3
(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 several widely scattered sites in the western half of the state. Trend data are lacking. Threats to populations do not appear to be significant at this time, though invasive weeds may eventually pose problems at some sites.
General Description
Bulbs sometimes clustered, globose; outer coat dingy white, membranous, honeycombed. Scapes terete, 20–35 cm. Leaves 2 to 3, subterete to channeled, 0.5–2 mm wide, withering. Umbel hemispheric with 10 to 30 flowers; pedicels 5–25 mm long; bracts 2, lanceolate to ovate, acuminate. Flowers pink to magenta; outer tepals 7–14 mm long; inner tepals smaller; ovary obscurely crested; stamens included. Seed surface minutely roughened (Lesica 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).

Flowering May-June.

Diagnostic Characteristics
Allium acuminatum can be distinguished from most other species by having the combination of rose-colored outer tepals that are longer than the inner tepals, and more than 2 concave leaves. The more common A. brevistylum also has rose-colored tepals, but its leaves are usually more than 4 mm wide.

Species Range
Montana Range


Range Comments
BC, MT south to CA, AZ and NM. Known from Ravalli and Sanders counties (Lesica 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).

Observations in Montana Natural Heritage Program Database
Number of Observations: 47

(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)

Dry, open forests and grasslands in the montane zone.
Predicted Suitable Habitat Model

This species has a Predicted Suitable Habitat Model available.

To learn how these Models were created see

  • Additional ReferencesLegend:   View Online Publication
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    • Lesica, P., M.T. Lavin, and P.F. Stickney. 2012. Manual of Montana Vascular Plants. Fort Worth, TX: BRIT Press. viii + 771 p.
    • Simanonok, M. 2018. Plant-pollinator network assembly after wildfire. Ph.D. Dissertation. Bozeman, MT: Montana State University. 123 p.
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Citation for data on this website:
Tapertip Onion — Allium acuminatum.  Montana Field Guide.  .  Retrieved on , from