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Pistia stratiotes

Basic information
Scientific name Pistia stratiotes

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Common names Water lettuce
Higher taxon Araceae, Alismatales, Liliopsida, Magnoliophyta
Natural range South Africa
Habitat Lake or pond, rice field, stream.
Invasion information
Range in Japan Kanto and Hokuriku District to western Japan. Ogasawara (Bonin) Islands. Range in Japan
Origin Unknown.
Date First introduction was in 1920s in Okinawa and Ogasawara. Infested on mainland since 1990s.
Route Deliberate: as ornamental plant. In past, many water Water lettuces were imported and cultivated, and distributed in Japan.
Impact Competition with native plants and rice. Water pollution. Inhibition of water current. Allolopathy. Host for insects, land snails, and fungi.
Native organism(s) affected: Native aquatic plants and rice.
Regulation in Japan Import, transport and keeping are prohibited in Japan by the Invasive Alien Species Act.
Introduced range in other countries Asia, Australia, North and Latin America
Reference Notes
  • Ecol Soc Jpn (ed) (2002) Handbook of Alien Species in Japan. Chijinshokan, Tokyo (in Jpn)
  • Shimizu (ed) (2003) Naturalized Plants of Japan. Heibonsha, Tokyo (in Jpn)
  • etc.
100 of the Japan’s Worst Invasive Alien Species