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Montana Field Guide

Montana Field Guides

Onerow Watercress - Rorippa microphylla
Other Names:  Nasturtium microphyllum

Non-native Species

Global Rank: GNR
State Rank: SNA
C-value: 1

Agency Status


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General Description
Perennial from fibrous-rooted rhizomes. Stems prostrate or floating, hollow, 10–50 cm long. Leaves all cauline, petiolate, 2–6 cm long; the blades pinnately compound with lanceolate to elliptic lateral lobes and an elliptic terminal segment. Petals white, 4–5 mm long. Fruit a linear silique, 8–12 mm long, ca. 0.5 mm wide; style ca. 1 mm long; pedicels spreading to ascending, 8–12 mm long (Lesica et al. 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).

Range Comments
Introduced in much of north-temperate North America, native to Europe (Lesica et al. 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).

Observations in Montana Natural Heritage Program Database
Number of Observations: 4

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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 rufocinctus (Thorp et al. 1983).


  • Literature Cited AboveLegend:   View Online Publication
    • Lesica, P., M.T. Lavin, and P.F. Stickney. 2012. Manual of Montana Vascular Plants. Fort Worth, TX: BRIT Press. viii + 771 p.
    • Thorp, R.W., D.S. Horning, and L.L. Dunning. 1983. Bumble bees and cuckoo bumble bees of California (Hymenoptera: Apidae). Bulletin of the California Insect Survey 23:1-79.
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Citation for data on this website:
Onerow Watercress — Rorippa microphylla.  Montana Field Guide.  .  Retrieved on , from