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Montana Field Guide

Montana Field Guides

Winged-loosestrife - Lythrum alatum

Undetermined Origin

Global Rank: G5
State Rank: SU
(see State Rank Reason below)

Agency Status


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State Rank Reason (see State Rank above)
Not conclusively documented from the state though likely to be found in extreme eastern Montana.
General Description
Stems 4-angled, 40–120 cm. Herbage glabrate. Leaves lanceolate to ovate, 15–60 mm long. Inflorescence of solitary, short-pedicellate flowers in axils of reduced upper leaves. Flowers: hypanthium puberulent, 5–7 mm long; petals 6, 3–6 mm long; stamens 6 (Lesica et al. 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).

Our plants are variety alatum.

Range Comments
MT to QC south to TX, MS, FL. One unconfirmed collection from Carter County (Lesica et al. 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).


The following animal species have been reported as pollinators of this plant species or its genus where their geographic ranges overlap: Bombus fervidus, Bombus ternarius, Bombus bimaculatus, Bombus griseocollis, and Bombus impatiens (Plath 1934, Colla and Dumesh 2010, Colla et al. 2011, Williams et al. 2014).

  • Literature Cited AboveLegend:   View Online Publication
    • Colla, S., L. Richardson, and P. Williams. 2011. Bumble bees of the eastern United States. Washington, DC: USDA Forest Service, Pollinator Partnership. 103 p.
    • 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.
    • Lesica, P., M.T. Lavin, and P.F. Stickney. 2012. Manual of Montana Vascular Plants. Fort Worth, TX: BRIT Press. viii + 771 p.
    • Plath, O.E. 1934. Bumblebees and their ways. New York, NY: Macmillan Company. 201 p.
    • Williams, P., R. Thorp, L. Richardson, and S. Colla. 2014. Bumble Bees of North America. Princeton, NJ: Princeton University Press. 208 p.
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Citation for data on this website:
Winged-loosestrife — Lythrum alatum.  Montana Field Guide.  .  Retrieved on , from