Johnston's Knotweed -
Polygonum douglasii ssp. johnstonii
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Annual. Stems erect, simple or branched at the base, 5–35 cm. Leaves short-petiolate; blades 8–20 mm long, linear-oblong, reduced above; stipules lacerate, 2–10 mm long. Flowers 3–4 mm long, 1 to 4 in leaf axils; pedicels erect, 1–4 mm long; tepals green with white to pink margins. Achene 3-sided, 2–3 mm long, shiny black (
Lesica et al. 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX
BC to SK south to CA, AZ and NM. One collection from an alpine, stony, calcareous slope in Beaverhead County (
Lesica et al. 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).
Observations in Montana Natural Heritage Program Database
Number of Observations:
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Map Help and Descriptions
(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:
(Macior 1974, Colla and Dumesh 2010).
Literature Cited Above
Legend: 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.