Calflora, a 501c3 non-profit
Distribution by County   266    
Alternanthera philoxeroides  (Mart.) Griseb.
Alligator weed,   Alligatorweed
Alternanthera philoxeroides is a perennial herb that is not native to California.
Cal-IPC rating: high
Record Count by County

Butte: 76 Riverside: 15 Santa Barbara: 1 Tulare: 114
Contra Costa: 47 Sacramento: 59 Shasta: 2 Yolo: 4
Kings: 102 San Bernardino: 1 Solano: 42
Los Angeles: 46 San Diego: 12 Stanislaus: 5
Orange: 1 San Joaquin: 20 Sutter: 3

Suggested Citation
Calflora: Information on California plants for education, research and conservation, with data contributed by public and private institutions and individuals, including the Consortium of California Herbaria. [web application]. 2026. The Calflora Database [a non-profit organization]. Available: https://www.calflora.org/   (Accessed: 01/18/2026).