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Montana Field Guide

Montana Field Guides

Broad Waterweed - Elodea canadensis


Global Rank: G5
State Rank: S4

Agency Status
USFWS:
USFS:
BLM:
MNPS Threat Rank:
C-value: 7

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General Description
Leaves 5–12 × 1.5–2.5 mm, minutely serrate, narrowly lanceolate and opposite below to more linear and 3-whorled above. Male flowers: spathe to 15 mm long, inflated above; sepals 3–5 mm long; petals 4–5 mm long; stamens 7 to 9. Female flowers: spathe 1–2 cm long, not inflated; sepals ca. 2 mm long, purplish; petals 2–3 mm long. Capsule 5–6 mm long (Lesica 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).

Diagnostic Characteristics
The native Elodea canadensis has dark green leaves that are often speckled with large dark cells (DiTomaso and Healy 2003). Middle and upper leaves are opposite or 3-whorled and those below the growing tips often curve slightly downward (DiTomaso and Healy 2003). Leaves are often relatively longer and narrower in comparison to exotic species. The mid-vein of each leaf is smooth on its underside (DiTomaso and Healy 2003). Roots are more wiry when compared to Hydrilla verticillata and Egeria densa.

The exotic species of Hydrilla verticillata also have whorled leaves, but in groups of 3-12 that are 6-20 mm long and 1-4 mm wide (DiTomaso and Healy 2003). Leaves below the growing tips are often curved downward (DiTomaso and Healy 2003). The mid-vein of each leaf is smooth or minutely toothed on its underside (DiTomaso and Healy 2003).

The exotic species of Egeria densa also has whorled leaves, but in groups of 3-8 that are 15-40 mm long and 2-5 mm wide. The mid-vein of each leaf is smooth or minutely toothed on its underside (DiTomaso and Healy 2003).

Species Range
Present
 


Range Comments
Throughout most of temperate N. America (Lesica 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).PLACEHOLDER (field is currently blank)

Summary of Observations Submitted for Montana
Number of Observations: 1648

(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
Shallow to deep water of lakes, ponds, sloughs, slow streams; valleys (Lesica 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).

Reproductive Characteristics
Axillary buds occur at nodes, at about 10 cm intervals (DiTomaso and Healy 2003).

References
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Citation for data on this website:
Broad Waterweed — Elodea canadensis.  Montana Field Guide.  .  Retrieved on , from