Dryopteris expansa
Common wood fern
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Family: Dryopteridaceae · Type: Herb · Native
Dryopteris expansa (Common wood fern) is a native California herb in the Dryopteridaceae family, recognized by . Distinguished by deltate blade shape and strongly unequal pinna sides.
Common wood fern is a California native perennial found in northern coastal, central coastal, and North Coast Ranges bioregions, including caves in Lava Beds National Monument, in shaded, wooded areas and stream banks at elevations up to 500 meters. As a distinctive fern, it has broadly triangular fronds 30 to 80 centimeters long with dark-colored leaf stalks and intricate scale patterns. Growing with large, complex fronds that are three-times pinnately divided, the plant forms expansive clusters with pinnae that are largest near the base of the frond. Its leaves feature asymmetrical side pinnules, with the lower-side pinnules more than twice the size of the upper-side pinnules on the same frond, creating an intricate layered green texture. The fern's segments are deeply lobed, with some segments featuring bristle-like teeth that add delicate texture to its overall structure.
Identification and appearance
Key characters: 1 sympatric species. Distinguished by deltate blade shape and strongly unequal pinna sides
Habitat and range
Habitat: Caves, shaded, wooded areas, especially banks of streams
Elevation: < 500 m (1300 m in MP)
Outside California: to Alaska, Canada, Rocky Mountains
How to tell it apart
vs Pteridium: Dryopteris has round spore covers on frond undersides; bracken fern has continuous spore lines hidden under rolled leaf edges.; vs Athyrium: Dryopteris spore covers are kidney-shaped and attached at the notch; lady ferns have curved, elongated spore clusters.; vs Polystichum: Run your hand along the frond—Dryopteris feels smooth, Polystichum feels distinctly prickly from bristle-tipped teeth.; vs Polypodium: Dryopteris has kidney-shaped covers over spore dots; polypody has naked round spore dots with no covering.; vs Woodwardia: Dryopteris has scattered round spore covers; chain fern has elongated spore clusters arranged in parallel chain-like rows.
Frequently asked questions
Is Dryopteris expansa native to California?
Yes. Dryopteris expansa is native to California (recorded as native).
What plant family does Dryopteris expansa belong to?
Dryopteris expansa is in the Dryopteridaceae family, genus Dryopteris.
What habitat does Dryopteris expansa grow in?
Dryopteris expansa grows in Caves, shaded, wooded areas, especially banks of streams.
Related species
Other California species in the same genus, family, or bioregion.
Sources: Jepson eFlora · 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.