Parrot Feather Identification & Treatment
Scientific Name: Myriophyllum aquaticum Category: Emergent / Submerged Tier: 2 — Regionally Significant — Common in multiple EPA ecoregions
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Identification
Parrot feather has distinctive feathery, bright green leaves arranged in whorls of 4–6 around the stem. The emergent (above-water) leaves are stiff, waxy, and stand upright like small bottle brushes — very different from the limp, feathery submerged leaves of native milfoils. The overall appearance is lush and decorative, which is why it was originally sold as an ornamental aquarium and water garden plant. Key distinguishing features:
- Stiff, waxy, feathery emergent leaves that stand above water
- Bright green (almost blue-green) color
- Whorls of 4–6 feathery leaves
- Emergent growth extends 6–12 inches above water surface
- Only female plants exist in the US
Treatment
Recommended Natural Waterscapes Products:
- Glyphosate 5.4 — Applied to emergent foliage. Most effective option because it translocates to roots. Glyphosate 5.4
- Clearcast (imazamox) — Systemic herbicide for emergent and floating growth. Clearcast
- Harvester (diquat) — Contact herbicide for foliage knockdown only.
Important: The waxy coating on emergent leaves makes herbicide uptake difficult. Use a surfactant with glyphosate applications. Multiple treatments are typically needed.
Full Profile
- Native Range: South America
- US Distribution: Found in southern and western states, expanding. EPA ecoregions: Southeastern Plains, Southern Coastal Plain, Central California Valley, Marine West Coast Forests. USDA Zones 6–11.
- Regulatory Status: Listed as noxious or invasive in many states. Federal Noxious Weed.
- Habitat: Ponds, lakes, streams, ditches, water garden escapes. Grows in shallow water margins and can colonize moist soil.
- Reproduction: Strictly vegetative in the US (all plants are female). Spreads by fragmentation — very aggressive.
- Ecological Benefits: Limited. Provides some invertebrate habitat. Primarily an ornamental escapee with negative ecological impacts.
- Seasonal Behavior: Semi-evergreen in mild climates. Dies back to the waterline in hard freezes. Regrows rapidly from surviving roots and fragments.
Sources: Texas A&M AquaPlant – Parrot Feather | MSU Extension
Related Species
- Sago Pondweed (Stuckenia pectinata (formerly Potamogeton pectinatus)) — Submerged, Tier 2
- Bladderwort (Utricularia spp.) — Submerged (free-floating), Tier 2
- Cabomba (Fanwort) (Cabomba caroliniana) — Submerged, Tier 2
- Water Lettuce (Pistia stratiotes) — Floating, Tier 2
- Dollar Weed (Pennywort) (Hydrocotyle spp. (H. umbellata, H. ranunculoides, H. verticillata)) — Emergent, Tier 2
- Alligator Weed (Alternanthera philoxeroides) — Emergent, Tier 2
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