Unwanted Organism, National Pest Plant Accord
- Scientific Name: Egeria densa
- Origin: Introduced plant. Native to South America
- Type: Weed
- Plant Life-form Type: Submerged
- Taxonomy: Planchon
- Presence: Widely naturalised in North Island and Marlborough. Few sites elsewhere in South Island, first record from the lower Waikato River in 1946
- Habitat: Moderate flowing to still water bodies, usually in moderately to highly enriched water bodies
- Notes: Major impacts on indigenous plant biodiversity, hydrogeneration, irrigation, flood protection and recreation.
- Propagation: Egeria propagates from stem fragments containing lateral buds that give rise to new plants. Egeria does not produce seed in New Zealand, with only male flowering plants being present
- Features: Submerged perennial. Leaves usually in whorls of 4-5 (sometimes 3-8). Leaves 10-30mm long, narrowing to an acute tip. Egeria is the only oxygen weed with visible white flowers.
- Source: TIFBIS
- Regional: Regional Pest Management Strategy: AUK, BOP, NSN/TAS, STL, WTC, MWT, CAN, HKB, MBH, TKI.