Elodea (Common Waterweed) Identification & Treatment
Scientific Name: Elodea canadensis Category: Submerged Tier: 1 — High-Priority — Most prevalent and/or most damaging across the US
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Identification
Elodea has small, oblong, bright green leaves arranged in whorls of 3 around the stem. Leaves are about 1/2 inch long, slightly translucent, with smooth margins and a bluntly pointed tip. Stems are slender, branching, and flexible. Produces tiny white flowers on thread-like stalks at the water surface. Key distinguishing features:
- Leaves in whorls of 3 (key distinguishing feature)
- Smooth leaf margins (no serrations)
- Smaller and more delicate than hydrilla or egeria
- No tubers or turions
Commonly confused with: Hydrilla (whorls of 4–8, serrated margins, midrib spines), Egeria (whorls of 4–6, larger leaves)
Treatment
Recommended Natural Waterscapes Products:
- Aquathol K or Aquathol Super K (endothall) — Contact herbicide, effective on elodea.
- Harvester (diquat) — Contact herbicide for quick knockdown.
- Sonar A.S. (fluridone) — Systemic option for season-long control.
Full Profile
- Native Range: Native to North America
- US Distribution: All 48 contiguous states. All EPA ecoregions. USDA Zones 3–10.
- Regulatory Status: Not regulated in the US (native species). Ironically, it is a serious invasive in Europe, Australia, and New Zealand.
- Habitat: Lakes, ponds, streams, rivers. Tolerates a range of conditions. Grows in 2–12 feet of water.
- Reproduction: Almost entirely by fragmentation and vegetative growth. Seeds are rare.
- Ecological Benefits: Excellent native aquatic plant with high ecological value. Important fish habitat (spawning substrate and juvenile cover). Oxygenates water through photosynthesis. Food for waterfowl, turtles, and aquatic invertebrates. In moderate densities, elodea is a desirable component of pond plant communities and generally should not be treated unless excessive.
- Seasonal Behavior: Active growth spring through fall. Dies back in winter in northern regions. Can persist year-round in warmer areas.
Sources: Texas A&M AquaPlant – Elodea | USDA PLANTS Database
Related Species
- Hydrilla (Hydrilla verticillata) — Submerged, Tier 1
- Eurasian Watermilfoil (Myriophyllum spicatum) — Submerged, Tier 1
- Coontail (Hornwort) (Ceratophyllum demersum) — Submerged, Tier 1
- Curly-Leaf Pondweed (Potamogeton crispus) — Submerged, Tier 1
- Egeria (Brazilian Elodea) (Egeria densa) — Submerged, Tier 1
- Sago Pondweed (Stuckenia pectinata (formerly Potamogeton pectinatus)) — Submerged, Tier 2
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