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(Pondweed family)


• Medicinal / Folk-medicinal aspects: •
• Adverse effects: Skin irritation has been reported following contact with plant material. •
• Veterinary aspects: •

The family comprises 115 species of submerged or floating freshwater (and also some brackish water) pondweeds in 7 genera. The majority (about 100 species) belong to the genus Potamogeton L. Precise botanical identification can be difficult because of their tendency to form interspecific hybrids (Mabberley 2008). The plants have been classified in the Najadaceae by some authorities.

Many are noxious weeds in the wild; a few are cultivated, not as decorative plants but as pond oxygenators (Hunt 1968/70).

Potamogeton crispus L.
Water Caltrop, Curly Pondweed, Curlyleaf Pondweed

[Information available but not yet included in database]

The common name caltrop refers to the capacity of these plants to entangle swimmers. Groenlandia densa Fourr. (syn. Potamogeton densus L.) and perhaps other species are also known by the common name water caltrop. The plants should not be confused with the botanically unrelated caltrop (Tribulus terrestris L.) of the family Zygophyllaceae.

Potamogeton illinoensis Morong
[syns Potamogeton angustifolius Bercht. & C.Presl, Potamogeton heterophyllus Schreb.]
Illinois Pondweed

Skin irritation by this plant while fishing is known to Fish and Wildlife authorities. A man and wife who fished from a boat in a freshwater lake in Florida noted irritation after removing weeds from their fishing tackle. This species was identified as the cause of the reaction (Morton 1976).


  • Hunt P (Ed.) (1968/70) The Marshall Cavendish Encyclopedia of Gardening. London: Marshall Cavendish [WorldCat]
  • Mabberley DJ (2008) Mabberley's Plant-Book. A portable dictionary of plants, their classification and uses, 3rd edn. Cambridge: Cambridge University Press [WorldCat]
  • Morton JF (1976) Personal communication to Mitchell JC. In: Mitchell J, Rook A (1979). Botanical Dermatology. Plants and plant products injurious to the skin. Vancouver: Greengrass, p. 544 [WorldCat]
  • [ + 3 further references not yet included in database]

Richard J. Schmidt

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