Montana Field Guide

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 et al. 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).

Flowering May-June.

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.

Dry, open forests and grasslands in the montane zone.

POLLINATORS
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).

STATE THREAT SCORE REASON
Reported threats to Montana’s populations of Tapertip Onion include severe potential threats to roadside populations if a road widening project takes place without mitigation. More than half of the state populations are located along a highway where proposed road construction may potentially damage or destroy plants, populations and habitat. Information on the status of this project, or knowledge of the population's existing condition is needed. Noxious weeds are reported to threaten other populations, where negative impacts due to chemical herbicide application are also a concern. Another potential threat due to development of recreation areas was reported, but information about the scope, severity, and timing is needed to assess its relative risk (MTNHP Threat Assessment 2021).