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Ireland: Kerry - Dublin - Cork - Waterford - Roscommon - Galway - Belfast
UK: London - Manchester - Newcastle - Cardiff - Liverpool
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Curly Waterweed - Invasive Species Information
What Is Curly Waterweed - (Lagarosiphon major)?
Habitat: Aquatic, fresh water
Distribution in Ireland: Sparse distribution but locally abundant in some places
Status: Established
Family name: Hydrocharitaceae
Reproduction: All reproduction is by fragmentation or vegetative reproduction. Detached stems, when they sink, root from the nodes and establish new populations
![JKK - High Risk Sign Red 19.gif](https://static.wixstatic.com/media/d4f7d5_c29af618a393487181ac74eae30e28dc~mv2.gif)
![Curly Waterweed - (Lagarosiphon major)](https://static.wixstatic.com/media/9b670b_4dd74b3e0ae943f8910e9ae3fe3b4a9c~mv2.jpg/v1/crop/x_106,y_0,w_245,h_375/fill/w_207,h_206,al_c,q_80,usm_0.66_1.00_0.01,enc_auto/9b670b_4dd74b3e0ae943f8910e9ae3fe3b4a9c~mv2.jpg)
Curly Waterweed
Originally from Southern Africa, where it is regarded as a nuisance weed.
The plant can grow in water up to 6m deep.
Curly waterweed is a perennial, submerged dioecious plant with branched stems and strongly recurved leaves alternate or spiralled or rarely in whorls up the stem, with two rows of fibre-like cells on the margins with > 50 teeth on each side.
It occurs in still or very slow-flowing water, principally in eutrophic, calcareous canals, ponds, lakes and gravel pits.
How To Identify Curly Waterweed?
Leaves: Strongly recurved dark green leaves borne in a spiral arrangement, slight yellow tinge from the underside.
Stem: The long stem is brittle and easily broken (aiding dispersal).
Size: Can grow in water up to 6 metres deep
![Curly Waterweed Leaf](https://static.wixstatic.com/media/9b670b_3e83c14ad76c4455a2c4bf30ab72cab8~mv2.jpg/v1/crop/x_37,y_0,w_378,h_432/fill/w_86,h_98,al_c,q_80,usm_0.66_1.00_0.01,blur_3,enc_auto/9b670b_3e83c14ad76c4455a2c4bf30ab72cab8~mv2.jpg)
![Lough Corrib Ireland After Infestation](https://static.wixstatic.com/media/9b670b_70582472c5b249a395eeeb9340747443~mv2.jpg/v1/crop/x_0,y_0,w_508,h_327/fill/w_152,h_98,al_c,q_80,usm_0.66_1.00_0.01,blur_3,enc_auto/9b670b_70582472c5b249a395eeeb9340747443~mv2.jpg)
![Lough Corrib Ireland Before Infestation](https://static.wixstatic.com/media/9b670b_52bb2c490c2042e09717c060281e2ec8~mv2.jpg/v1/crop/x_0,y_61,w_423,h_285/fill/w_145,h_98,al_c,q_80,usm_0.66_1.00_0.01,blur_3,enc_auto/9b670b_52bb2c490c2042e09717c060281e2ec8~mv2.jpg)
![Curly Waterweed - Lagarosiphon major ID Guide](https://static.wixstatic.com/media/d4f7d5_1866c4b2998544ba9de937a16f3628b8~mv2.gif)
Curly Waterweed - Lagarosiphon major ID Guide
Lough Corrib Ireland Before Infestation
Lough Corrib Ireland After Infestation
Curly Waterweed Leaf
![Waterweed ID.gif](https://static.wixstatic.com/media/d4f7d5_9493617e3b89478385652217c67ae771~mv2.gif)
Why Is Curly Waterweed A Problem?
Plant stands produce dense canopy vegetation on the water surface and displaces native species.
In high densities it blocks light from penetrating the water leading to a disturbance in the food web and a decrease in biodiversity.
It interferes with commercial navigation and water-based recreation. It has a negative impact on some native fish species. Native macroinvertebrate community structures are altered.
National Biodiversity Data Centre Ireland - Recognised Invasive Plant Species.
There are currently 35 invasive plant species identified as high risk on Ireland's biodiversity control list. Here's the A to Z of plant species included on the list (updated 2017)...
Click on a species from the following list to find out more
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American Skunk-Cabbage - Lysichiton americanus
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Red Alga - Grateloupia doryphora
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Waterweeds - Elodea (all species)