Adiantum aleuticum
Five-finger fern
(c) Ed Alverson, some rights reserved (CC BY) · licence
Family: Pteridaceae · Type: Herb · Native
Adiantum aleuticum (Five-finger fern) is a native California herb in the Pteridaceae family, recognized by elevation and pinnule lobing patterns.
Five-finger fern is a California native perennial found in northwestern California, California Mountains, Coast Ranges, San Francisco Bay Area, southern Coast Ranges, northern Channel Islands, Transverse Ranges, and San Jacinto Mountains on shady, moist banks and streamsides at elevations below 3,400 meters. Its distinctive fronds reach 20 to 75 centimeters long with red-brown to nearly black stems, creating a delicate palmate-pinnate blade structure. Growing with an elegant, fan-like form, this fern features pinnules with more than 4 regular lobes, typically cut less than halfway to the midrib. Its pinnule margins converge at a 45 to 90 degree angle, creating an intricate geometric pattern across the frond. Sporangia clusters form 4 to 6 per pinnule, typically less than 3 millimeters wide, highlighting the fern's delicate reproductive structure.
Identification and appearance
Key characters: 2 sympatric species; elevation and pinnule lobing patterns are diagnostic
Habitat and range
Habitat: Shady, moist banks, streamsides, serpentine
Elevation: < 3400 m
California counties: Mendocino, Plumas, Sonoma, Trinity, San Mateo, Placer, Santa Cruz, Siskiyou, Santa Barbara, San Bernardino, Yuba, Riverside, Santa Clara, San Luis Obispo, Los Angeles, Butte, Del Norte, Fresno, Humboldt, Inyo, Madera, Monterey, Nevada, Shasta, Tulare, Tuolumne, Mariposa, Sierra, Amador, Alpine, Marin, El Dorado, Mono, Napa, Tehama, Alameda
Outside California: to Alaska, western Canada, Montana, Colorado, New Mexico, eastern United States, adjacent Can, northwestern Mexico
How to tell it apart
vs Polystichum: Adiantum has fan-shaped leaflets on black stems; sword ferns have narrow pointed segments on brown stems.; vs Pellaea: Feel the leaflet - Adiantum is thin and delicate, Pellaea is thick and leathery.; vs Thalictrum: Adiantum has spore cases under rolled leaf edges; meadow-rue has flowers and seeds, not spores.; vs Polypodium: Adiantum has fan-shaped leaflets with spores under margins; polypody has elongated segments with round sori.; vs Pentagramma: Adiantum leaflets are thin and delicate; goldback fern leaflets are thicker with powder underneath.
Frequently asked questions
Is Adiantum aleuticum native to California?
Yes. Adiantum aleuticum is native to California (recorded as native).
Where in California does Adiantum aleuticum grow?
Adiantum aleuticum occurs in Mendocino, Plumas, Sonoma, Trinity, San Mateo, Placer, Santa Cruz, Siskiyou and other counties, at elevations of < 3400 m.
What plant family does Adiantum aleuticum belong to?
Adiantum aleuticum is in the Pteridaceae family, genus Adiantum.
What habitat does Adiantum aleuticum grow in?
Adiantum aleuticum grows in Shady, moist banks, streamsides, serpentine.
Related species
Other California species in the same genus, family, or bioregion.
Sources: Jepson eFlora · Index of California Plant Names · CalPhotos
Last updated 2026-10-07
Data from The California Species Project — 14,000+ California species with verified data from CNPS, CDFW, USFWS, Cal-IPC, and more.