top of page

Fanwort - Invasive Species Information

JKK - High Risk Sign Red 18.gif

What Is Fanwort - (Cabomba caroliniana)?

Habitat: Aquatic, Lakes, ponds and fast and slow flowing rivers
Distribution in Ireland: Sparse distribution but locally abundant in some places.

Status: Established
Family name: Cabombaceae

Fanwart - Cabomba caroliniana submerged plant

Reproduction: Fanwort reproduces

by both vegetative methods and

seed formation.

  • Vegetatively, - reproduces by 
    stem (rhizome) fragmentation.
    Stems are very fragile, fragment easily and most pieces can re-sprout and grow into new plants

  • Seeds are also formed, and Fanwort can re-grow from seeds remaining in lake or pond sediment 

Fanwort Fond

Native to South America and southern parts of North America, Fanwort is a submerged invasive aquatic plant that can form dense mats at the water surface.


The delicate green underwater leaves are fan-like and average 5 cm across. Leaves are arranged in opposite pairs on the stem. Small oval floating leaves are occasionally present. Small diamond-shaped floating leaves with the stem attached in the center may develop. Tubular stems can attain lengths of 2m.

Why Is Fanwort A Problem?

Fanwort is a highly competitive plant that is capable of rapid growth and spread. It can displace native species, reduce biodiversity, hamper recreational uses, reduce real estate value, diminish aesthetic values, and decrease water quality.


Once established, Fanwort can negatively impact and out-compete native vegetation. Fish and animals that were dependent on the native vegetation must relocate or perish, leading to a decline

in biodiversity.


Fanwort can greatly impede boaters, fisherman, water skiers and swimmers, and these limitations on water use can negatively impact real estate values.


Fanwort produces dense large mats of vegetation on the water surface, thus intercepting sunlight to the exclusion of other submerged plants.


Sediment levels increase with increasing Fanwort abundance.


When dense mats of Fanwort decay, the available oxygen in the water may be depleted. The resulting low oxygen conditions (anoxic) can lead to fish kills and harm other aquatic organisms. 

How To Identify Fanwort?

Stem: Tubular stems

Flowers: 1.5cm white or cream flowers form during May through September; Some variations of Fanwort have pinkish/purplish flowers 

Size: Can grow up to 2 metres 

Fanwort - Cabomba caroliniana ID Guide
Fanwart - Cabomba caroliniana Leaves
Fanwart - Cabomba caroliniana leaf detail
Fanwart - Cabomba caroliniana leaf brown
Fanwart - Cabomba caroliniana flower

Fanwort - Cabomba caroliniana ID Guide



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

bottom of page