Alternanthera philoxeroides

Basic information
Scientific name	Alternanthera philoxeroides	Click to magnify
Common names	Alligatorweed
Higher taxon	Amaranthaceae, Caryophyllales, Magnoliopsida, Magnoliophyta
Natural range	South America.
Habitat	Channel, stream, swamp, etc.

Invasion information
Range in Japan	Fukushima, Ibaraki, Saitama, Tokyo, Chiba, Kanagawa, Yamanashi, Shizuoka, Aichi, Mie, Fukui, Shiga, Nara, Kyoto, Osaka, Hyogo, Okayama, Awaji Island, Tottori, Shimane, Yamaguchi, Kagawa, Tokushima, Ehime, Fukuoka, Saga, Nagasaki, Kumamoto, Kagoshima, and Okinawa Prefs.
Origin	Unknown.
Date	The first record in Japan was in 1989 at Amagasaki, Hyogo Pref.
Route	Deliberate: Escape of aquarium ornament.
Impact	Competition with native species. Disturbance of boat operation. Native organism(s) affected: Native aquatic plants
Regulation in Japan	Import, transport and keeping are legally restricted in Japan.
Introduced range in other countries	Taiwan, Australia, Libya, USA, etc.

Reference

Notes

Tanaka (1992) Alternanthera philoxeroides (Mart.) Griseb., a new naturalized plant from Amagasaki City. Hyoko Biology. 10, 107-108 (in Jpn)
DECO (ed) (2006) Dictionary of Alien Species. Tokyo-Shoseki. (in Jpn)
GBIF Portal http://data.gbif.org/welcome.htm
InvasivePlant.net http://www.invasiveplants.net/
JWRC (ed) (2008) A Photographic Guide to the Invasive Alien Species in Japan. Heibonsha. (in Jpn)
etc.
Okayama Prefecture (Accessed on 2025-4-10)
Japan Agricultural Communications (Accessed on 2025-07-23)