Waterweeds - Invasive Species Information
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Elodea bifoliata H.St.John
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Elodea callitrichoides (Rich.) Casp
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Elodea canadensis Michx.
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Elodea granatensis Humb. & Bonpl
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Elodea nuttallii (Planch.) H.St.John
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Elodea potamogeton (Bertero) Espinosa
Habitat: Aquatic. Ponds, Canals, Rivers and Lakes
Distribution in Ireland: Extensive distribution throughout Irelands waterways
Status: Established
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
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
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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.
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American Skunk-Cabbage - Lysichiton americanus
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Brazilian Giant-Rhubarb - Gunnera manicata
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Broad-Leaved Rush - Juncus planifolius
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Cape Pondweed - Aponogeton distachyos
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Cord-Grasses - Spartina (all species and hybrids)
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Curly Waterweed - Lagarosiphon major
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Dwarf Eel-Grass - Zostera japonica
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Fanwort - Cabomba caroliniana
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Floating Pennywort - Hydrocotyle ranunculoides
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Fringed Water-Lily - Nymphoides peltata
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Giant Hogweed - Heracleum mantegazzianum
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Giant Knotweed - Fallopia sachalinensis
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Giant-Rhubarb - Gunnera tinctoria
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Giant Salvinia - Salvinia molesta
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Himalayan Balsam - Impatiens glandulifera
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Himalayan Knotweed - Persicaria wallichii
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Hottentot-Fig - Carpobrotus edulis
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Japanese Knotweed - Fallopia japonica
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Large-Flowered Waterweed - Egeria densa
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Mile-a-Minute Weed - Persicaria perfoliata
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New Zealand Pigmyweed - Crassula helmsii
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Parrots Feather - Myriophyllum aquaticum
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Red Alga - Grateloupia doryphora
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Rhododendron - Rhododendron ponticum
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Salmonberry - Rubus spectabilis
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Sea-Buckthorn - Hippophae rhamnoides
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Spanish Bluebell - Hyacinthoides hispanica
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Three-Cornered Leek - Allium triquetrum
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Wakame - Undaria pinnatifida
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Water Chestnut - Trapa natans
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Water Fern - Azolla filiculoides
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Water Lettuce - Pistia stratiotes
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Water-Primrose - Ludwigia (all species)
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Waterweeds - Elodea (all species)
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Wireweed - Sargassum muticum