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Waterweeds - Invasive Species Information

  1. Elodea bifoliata H.St.John

  2. Elodea callitrichoides (Rich.) Casp

  3. Elodea canadensis Michx.

  4. Elodea granatensis Humb. & Bonpl

  5. Elodea nuttallii (Planch.) H.St.John

  6. Elodea potamogeton (Bertero) Espinosa

HabitatAquatic. Ponds, Canals, Rivers and Lakes
Distribution in Ireland: Extensive distribution throughout Irelands waterways

StatusEstablished
Family name: Hydrocharitaceae

Reproduction: water weed lives entirely underwater with the exception of small white flowers which bloom at the surface and are attached to the plant by delicate stalks. It produces winter buds from the stem tips that overwinter at the bottom of water bodies.

Waterweed Leaves

Waterweed Leaves

Waterweeds often overwinters as an evergreen plant in mild climates. In Autumn, leafy stalks will detach from the parent plant, float away, root, and start new plants.

 

This is the American water weed's most important method of spreading, while seed production plays a relatively minor role.

The introduction of some species of Elodea into waterways in parts of Europe, Australia, Africa, Asia, and New Zealand has created a significant problem and it is now considered a noxious weed in these areas. An older name for this genus is Anacharis, which serves as a common name in North America.

How To Identify Waterweeds?

Leaf: Green leaf submerged

Flower: Small white flower at water surface  

Waterweed Infestation
Waterweed Leaves and Bud

Waterweed Infestation

Waterweed Leaves

Why Is Waterweed A Problem?

Waterweeds can been found growing in a wide range of water bodies: lakes, reservoirs, ponds, rivers streams, canals and ditches.

 

It tends to dominate native macrophyte communities which may lead to their local extinction. Waterweeds are also known to replace other invasive species as the dominant species in an impacted ecosystem.

 

More recent data suggests that Elodea Waterweed species are now becoming replaced by another introduced species Curly Waterweed - Lagarosiphon major. It is tolerant of disturbance, oil pollution and salinity up to 14 parts per thousand (approx. half seawater). All Elodea (Waterweed) species tend to take up metals from the sediment and release them into the water. Elodea nuttallii is very tolerant of copper in particular. 

What Are Waterweeds - (Elodea) (all species)?

European Communities (Birds and Natural Habitats) Regulations 2011 non-native invasive plant species A-Z (Updated 2017)

There are currently 35 invasive plant species listed in the European Communities (Birds and Natural Habitats) Regulations (annex 2, Part 1)...

 

Click on a species from the following list to find out more regarding non-native species subject to restrictions under Regulations 49 and 50.

  1. American Skunk-CabbageLysichiton americanus

  2. Brazilian Giant-RhubarbGunnera manicata

  3. Broad-Leaved RushJuncus planifolius

  4. Cape PondweedAponogeton distachyos

  5. Cord-GrassesSpartina (all species and hybrids)

  6. Curly Waterweed - Lagarosiphon major

  7. Dwarf Eel-GrassZostera japonica

  8. FanwortCabomba caroliniana

  9. Floating PennywortHydrocotyle ranunculoides

  10. Fringed Water-LilyNymphoides peltata

  11. Giant HogweedHeracleum mantegazzianum

  12. Giant KnotweedFallopia sachalinensis

  13. Giant-RhubarbGunnera tinctoria

  14. Giant SalviniaSalvinia molesta

  15. Himalayan BalsamImpatiens glandulifera

  16. Himalayan KnotweedPersicaria wallichii

  17. Hottentot-FigCarpobrotus edulis

  18. Japanese KnotweedFallopia japonica

  19. Large-Flowered WaterweedEgeria densa

  20. Mile-a-Minute WeedPersicaria perfoliata

  21. New Zealand PigmyweedCrassula helmsii

  22. Parrots FeatherMyriophyllum aquaticum

  23. Red AlgaGrateloupia doryphora

  24. RhododendronRhododendron ponticum

  25. SalmonberryRubus spectabilis

  26. Sea-Buckthorn Hippophae rhamnoides

  27. Spanish Bluebell Hyacinthoides hispanica

  28. Three-Cornered LeekAllium triquetrum

  29. WakameUndaria pinnatifida

  30. Water ChestnutTrapa natans

  31. Water FernAzolla filiculoides

  32. Water LettucePistia stratiotes

  33. Water-PrimroseLudwigia (all species)

  34. WaterweedsElodea (all species)

  35. WireweedSargassum muticum