Azolla filiculoides

American water fern

Family: Azollaceae · Type: Fern · Native

American water fern is a native aquatic fern found in California's Foothills Periphery, Great Basin, and Mojave Desert regions in ponds and slow-moving streams at elevations below 1,300 meters. Often displaying a distinctive green to reddish coloration, this small fern grows in prostrate and ascending forms with stems generally 1 to 3 centimeters long. Growing with delicate, tiny leaves that are smooth or bearing inconspicuous papillae on the upper leaf lobes, the plant creates dense floating mats across water surfaces. Its growth pattern is characterized by very short internodes, with mature plants developing ascending stems less than 1 millimeter between leaf attachments. The plant produces both male and female sporangium cases, often with a distinctive equatorial girdle and tubercled, pitted wall structure.

Habitat: Common. Ponds, slow streams

Elevation: < 1300 m

Bioregions: CA-FP, GB, DMoj(?)

California counties: Tulare, Ventura, Los Angeles, Riverside, San Bernardino, Alameda, Butte, Colusa, Fresno, Glenn, Humboldt, Inyo, Kern, Lake, Madera, Mendocino, Modoc, Mono, Monterey, Orange, San Diego, San Francisco, San Joaquin, San Luis Obispo, San Mateo, Santa Barbara, Santa Clara, Santa Cruz, Sonoma, Stanislaus, Mariposa, Merced, Marin, San Benito, Yuba, Tehama, Yolo, Placer, Napa, Contra Costa, Sacramento

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