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Montana Field Guide

Montana Field Guides

Engelmann's Knotweed - Polygonum engelmannii
Other Names:  Polygonum douglasii ssp. engelmannii

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Status Under Review
Native Species

Global Rank: G5T3T5
State Rank: SNR
C-value: 4

Agency Status


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General Description
Annual. Stems erect or ascending, angled, branched at the base, 2–10 cm. Leaves short-petiolate; the blades 5–15 mm long, linear-oblanceolate, reduced above; stipules glabrous, 2–3 mm long. Flowers ca. 2 mm long, 2 to 4 in upper leaf axils; pedicels reflexed, 1–3 mm long; tepals green with rose margins. Achene 3-sided, 1–2 mm long, shiny black (Lesica et al. 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).

Species Range

Range Comments
BC, AB south to NV, UT and CO (Lesica et al. 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).

Observations in Montana Natural Heritage Program Database
Number of Observations: 1

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Relative Density



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


The following animal species have been reported as pollinators of this plant species or its genus where their geographic ranges overlap: Bombus bifarius, Bombus flavifrons, Bombus frigidus, Bombus melanopygus, Bombus sylvicola, Bombus occidentalis, Bombus pensylvanicus, Bombus insularis, and Bombus kirbiellus (Macior 1974, Colla and Dumesh 2010).

  • 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.
    • 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.
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Citation for data on this website:
Engelmann's Knotweed — Polygonum engelmannii.  Montana Field Guide.  .  Retrieved on , from