Scientific Name:
Egeria densa Planch. (1849)
  • Anacharis densa (Planch.) Vict.
  • Elodea densa (Planch.) Casp.
Vernacular Name(s):
Dense waterweed; Egeria oxygen weed; Lakeweed

Vigorous submersed perennial. Stems branched, brittle, c. 3 mm diam. Leaves very dark green, in whorls of 3 below, in whorls of 4 or more above, 15–30 × 4 mm, linear, lax, abruptly acute to acuminate. Male flowers obvious, usually 2–3 per spathe in axils of upper leaves; sepals green c. 4 mm long, petals white, c. 7 mm long; stamens 9, golden. Female flowers and fruits not known in N.Z.

[From: Healy and Edgar (1980) Flora of New Zealand. Volume 3.]


Flowering: Nov.–Jan.

Biosecurity New Zealand 2012: Regional Pest Management Strategies Database.
Biosecurity New Zealand 4 Aug 2011: Unwanted Organisms Register.
Biosecurity New Zealand 2008: National Plant Pest Accord. MAF Biosecurity New Zealand, Wellington.
Howell, C. 2008: Consolidated list of environmental weeds in New Zealand. DOC Research & Development Series 292: 42.
Ministry for Primary Industries 23 Feb 2017: Unwanted Organisms Register. Version 02.01.02.