Egeria (Brazilian Elodea) Identification & Treatment
Scientific Name: Egeria densa Category: Submerged Tier: 1 — High-Priority — Most prevalent and/or most damaging across the US
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Identification
Egeria is a large, robust submerged plant with bright green, strap-like leaves in dense whorls of 4–6 around the stem. Leaves are about 1 inch long, larger and more tightly packed than native elodea. Stems are thick and can reach the surface, forming dense underwater meadows. Produces conspicuous white three-petaled flowers at the surface. Key distinguishing features:
- Leaves in whorls of 4–6, densely packed
- Leaves larger (about 1 inch) than elodea or hydrilla
- No serrations on leaf margins, no midrib spines
- Showy white 3-petaled flowers at surface
- Thick stems, overall more robust than elodea
Commonly confused with: Elodea (smaller leaves, whorls of 3), Hydrilla (serrated margins, midrib spines, tubers)
Treatment
Recommended Natural Waterscapes Products:
- Sonar A.S. or SonarOne (fluridone) — Most effective systemic option.
- Aquathol K (endothall) — Contact herbicide.
- Harvester (diquat) — Contact herbicide for spot treatment.
Full Profile
- Native Range: South America (Brazil, Argentina, Uruguay)
- US Distribution: Found in southern and western states — California, Oregon, Washington, southeastern states. EPA Ecoregions: Marine West Coast Forests, Willamette and Central Valley, Southern Coastal Plain, Southeastern Plains. USDA Zones 6–11.
- Regulatory Status: Listed as invasive or noxious in several states (California, Oregon, Washington, South Carolina, others). Federal Noxious Weed.
- Habitat: Lakes, ponds, slow rivers, canals. Prefers clear, warm, nutrient-moderate water.
- Reproduction: Fragmentation only (in the US, all plants are male — no seed production). Stem fragments root readily.
- Ecological Benefits: Provides good fish habitat structure and oxygenates water. Used in the aquarium trade. Dense infestations can impede navigation and recreation.
- Seasonal Behavior: Active growth spring through fall. Semi-evergreen in mild climates. Dies back in hard freezes.
Sources: Texas A&M AquaPlant – Egeria | 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
- Elodea (Common Waterweed) (Elodea canadensis) — Submerged, Tier 1
- Sago Pondweed (Stuckenia pectinata (formerly Potamogeton pectinatus)) — Submerged, Tier 2
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