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Montana Field Guides

Nuttall Waterweed - Elodea nuttallii

Native Species

Global Rank: G5
State Rank: S4
(see State Rank Reason below)
C-value: 4

Agency Status


External Links

State Rank Reason (see State Rank above)
Elodea nuttallii is an aquatic plant that occurs in western Montana. Populations appear to be relatively common and stable; however, half of the occurrences were found prior to 1967. Current data on population locations, sizes, and threats are needed.
  • Details on Status Ranking and Review
    Nuttall Waterweed (Elodea nuttallii) Conservation Status Review
    Review Date = 08/21/2018
    View State Conservation Rank Criteria
    Range Extent

    ScoreF - 20,000-200,000 sq km (~8,000-80,000 sq mi)

    Area of Occupancy

    ScoreE - 26-125 4-km2 grid cells

    Number of Populations

    ScoreC - 21 - 80

    Number of Occurrences or Percent Area with Good Viability / Ecological Integrity

    ScoreC - Few (4-12) occurrences with excellent or good viability or ecological integrity

    Environmental Specificity

    ScoreC - Moderate. Generalist or community with some key requirements scarce


    ScoreD - Low

    CommentNo known threats.

General Description
PLANTS: Aquatic.

LEAVES: Mostly whorled in groups of 3 or 4 (Lesica et al. 2012). Leaves are recurved, linear to lanceolate, and 4–15 × 1–1.5 mm, linear (FNA 2000; Lesica et al. 2012).

INFLORESCENCE: Male flowers occur in spathes that are somewhat spherical to ovoid, sessile, and 2.2-4.0 mm long; sepals about 2 mm long; petals minute or absent; stamens 9 (FNA 2000; Lesica et al. 2012). Female flowers occur in spathes that are linear and 9–15 mm long; sepals 1–2 mm long; petals 1–2 mm long (FNA 2000; Lesica et al. 2012). Capsules are 4–8 mm long (Lesica et al. 2012).

Flowers in summer (FNA 2000).

Range Comments
Throughout most of temperate North America (Lesica et al. 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).

Observations in Montana Natural Heritage Program Database
Number of Observations: 327

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



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

Shallow to deep water of ponds, lakes, sloughs (Lesica et al. 2012), mostly calcareous (FNA 2000). Valleys and montane (Lesica et al. 2012).

Not considered to be weedy in North America, but is weedy in Europe (FNA 2000).

  • Literature Cited AboveLegend:   View Online Publication
    • Flora of North America Editorial Committee (FNA). 2000. Flora of North America north of Mexico. Vol. 22. Magnoliophyta: Alismatidae, Arecidae, Commelinidae (in part), and Zingiberidae. Oxford Univ. Press, New York. xxiii + 352 pp.
    • Lesica, P., M.T. Lavin, and P.F. Stickney. 2012. Manual of Montana Vascular Plants. Fort Worth, TX: BRIT Press. viii + 771 p.
  • Additional ReferencesLegend:   View Online Publication
    Do you know of a citation we're missing?
    • Jeanes, E.D. 1996. Behavioral responses to water current of age-0 Arctic Grayling from the Madison River, and their use of stream habitat. M.Sc. Thesis. Bozeman, MT: Montana State University. 60p.
    • Lesica, P., M.T. Lavin, and P.F. Stickney. 2022. Manual of Montana Vascular Plants, Second Edition. Fort Worth, TX: BRIT Press. viii + 779 p.
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Citation for data on this website:
Nuttall Waterweed — Elodea nuttallii.  Montana Field Guide.  .  Retrieved on , from