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Montana Field Guide

Montana Field Guides

Large Knotweed - Polygonum majus
Other Names:  Polygonum douglasii ssp. majus

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Status Under Review
Native Species

Global Rank: G5T5
State Rank: SNR
C-value: 3


Agency Status
USFWS:
USFS:
BLM:


 

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General Description
Annual. Stems erect, angled, branched near the base, 8–60 cm. Leaves linear-lanceolate, 2–5 cm long; stipules glabrous, 6–10 mm long. Flowers 4–5 mm long, 2 to 4 in upper leaf axils; pedicels reflexed, ca. 1 mm long; tepals white to rose. Achene 3-sided, 3–5 mm long, black (Lesica et al. 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).

Species Range
Present
 


Range Comments
BC to CA, 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: 11

(Click on the following maps and charts to see full sized version) Map Help and Descriptions
Relative Density

Recency

 

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



Habitat
Grasslands, open forest, along roads; valleys, montane (Lesica et al. 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).

Ecology
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 flavifrons, Bombus frigidus, Bombus melanopygus, Bombus sylvicola, Bombus occidentalis, Bombus pensylvanicus, Bombus insularis, and Bombus kirbiellus (Macior 1974, Colla and Dumesh 2010).

References
  • 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:
Large Knotweed — Polygonum majus.  Montana Field Guide.  .  Retrieved on , from