Long-sheath Waterweed - Elodea bifoliata
State Rank Reason (see State Rank above)
Rare in Montana, where it is currently known from a few widely scattered locations across the state. Additional population and trend data are needed for the species within Montana.
Leaves opposite, 10–20 × 1.5–2.5 mm, minutely serrate, narrowly lanceolate to linear. Male flowers: spathe 2–5 cm long, inflated above; sepals 3–5 mm long; petals 4–5 mm long; stamens 7 to 9. Female flowers: spathe 3–7 cm long, slightly inflated above; sepals 2–3 mm long; petals 3–4 mm long. Capsule 8–10 mm long (Lesica et al. 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX
Flowering in late June-July.
Elodea can be distinguished from other aquatic plants by the long-stalked, floating flowers. Elodea bifoliata can be distinguished from other members of the genus by its opposite rather than whorled leaves.
BC to MN south to OR, UT and NM (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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(Observations spanning multiple months or years are excluded from time charts)
Shallow water of ponds and lakes on the plains.
Ecological Systems Associated with this Species
Threats or Limiting Factors
STATE THREAT SCORE REASON
Threat impact not assigned because threats are not known (MTNHP Threat Assessment 2021).
- 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.
- Additional ReferencesLegend: View Online Publication
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- Catling, P.M., and W. Wojtas. 1986. The waterweeds (Elodea and Egeria, hydrocharitaceae) in Canada. Can. J. Bot. 64:1525-1541.
- 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.