Salvinia molesta

Kariba weed

Family: Salviniaceae · Type: Fern · Not Native

Conservation status: Cal-IPC Yes

Kariba weed is a naturalized fern found in southern California and the Colorado River region in river channels, backwaters, and floodplain ponds at elevations generally below 100 meters. This invasive aquatic fern has distinctive floating leaves approximately 15 to 25 millimeters wide, nearly round and spreading across water surfaces. Growing as a floating plant with delicate, intricate leaf structures, it spreads quickly across water environments. Its leaves feature unique papillae on the upper surface, with tiny hairs that form dark knots at their tips, creating a distinctive textural appearance. When established, this aggressive species can rapidly colonize and cover water surfaces, forming dense floating mats.

Habitat: River channels, backwaters, floodplain ponds

Elevation: generally < 100 m

Bioregions: SCo, DSon (Colorado River)

California counties: Imperial, Orange, San Diego, San Luis Obispo, Riverside, Mendocino

Data from The California Species Project — 14,000+ California species with verified data from CNPS, CDFW, USFWS, Jepson eFlora, Cal-IPC, and more.