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Reproduction: The plant spreads by the rosettes and fruits detaching from the stem and floating to another area on currents or by fruits clinging to objects, and animals.

Water Chestnut - Trapa natans Leaves

Water Chestnut Leaves

The species are floating annual aquatic plants, growing in slow-moving water up to 5 m deep, native to warm temperate parts of Eurasia and Africa. They bear ornately shaped fruits, which resemble the head of a bull or the silhouette of a flying bat. Each fruit contains a single very large, starchy seed.

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This plant should not be confused with the unrelated Eleocharis dulcis, also called a water chestnut. Eleocharis is also an aquatic plant raised for food since ancient times in China. Eleocharis dulcis is a sedge, whose round, crisp-fleshed corms are common in Western-style Chinese food.

How To Identify Water Chestnut?

Leaf: Dark green serrated leaves

Fruit: "Bat-shaped" fruit

Water Chestnut - Trapa natans lake clearance
Water Chestnut - Trapa natans ID Guide

Water Chestnut - Trapa natans ID Guide

Water Chestnut Clean-up Operation

Why Is Water Chestnut A Problem?

Fasciolopsiasis is an ailment resulting from infection by the trematode Fasciolopsis buski, an intestinal fluke of humans, endemic in China, Taiwan, Southeast Asia, Indonesia, Malaysia, and India; this fluke can be transmitted via the surfaces of these and other water plants.

 

During the metacercarial stage in their lifecycle, the larval flukes leave their water snail hosts, and swim away to form cysts on the surfaces of water plants, including the leaves and fruit of water caltrops. If infected water plants are consumed raw or undercooked, the flukes can infect pigs, humans, and other animals.

Water Chestnut - Invasive Species Information

What Is Water Chestnut - (Trapa natans)?

Habitat: Aquatic
Distribution in Ireland: Inland lakes, ponds and canals, abundant in some places.

Status: Established
Family name: Lythraceae

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

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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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  1. American Skunk-Cabbage - Lysichiton americanus

  2. Brazilian Giant-Rhubarb - Gunnera manicata

  3. Broad-Leaved Rush - Juncus planifolius

  4. Cape Pondweed - Aponogeton distachyos

  5. Cord-Grasses - Spartina (all species and hybrids)

  6. Curly Waterweed - Lagarosiphon major

  7. Dwarf Eel-Grass - Zostera japonica

  8. Fanwort - Cabomba caroliniana

  9. Floating Pennywort - Hydrocotyle ranunculoides

  10. Fringed Water-Lily - Nymphoides peltata

  11. Giant Hogweed - Heracleum mantegazzianum

  12. Giant Knotweed - Fallopia sachalinensis

  13. Giant-Rhubarb - Gunnera tinctoria

  14. Giant Salvinia - Salvinia molesta

  15. Himalayan Balsam - Impatiens glandulifera

  16. Himalayan Knotweed - Persicaria wallichii

  17. Hottentot-Fig - Carpobrotus edulis

  18. Japanese Knotweed - Fallopia japonica

  19. Large-Flowered Waterweed - Egeria densa

  20. Mile-a-Minute Weed - Persicaria perfoliata

  21. New Zealand Pigmyweed - Crassula helmsii

  22. Parrots Feather - Myriophyllum aquaticum

  23. Red Alga - Grateloupia doryphora

  24. Rhododendron - Rhododendron ponticum

  25. Salmonberry - Rubus spectabilis

  26. Sea-Buckthorn - Hippophae rhamnoides

  27. Spanish Bluebell - Hyacinthoides hispanica

  28. Three-Cornered Leek - Allium triquetrum

  29. Wakame - Undaria pinnatifida

  30. Water Chestnut - Trapa natans

  31. Water Fern - Azolla filiculoides

  32. Water Lettuce - Pistia stratiotes

  33. Water-Primrose - Ludwigia (all species)

  34. Waterweeds - Elodea (all species)

  35. Wireweed - Sargassum muticum

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