California Maidenhair Fern

California Maidenhair Fern © DSchiel

Adiantum jordanii

Description (Jepson,

  • Fern (Polypodiopsida)       
    • Ferns are a early group of vascular plants that produce spores (reproductive cells)
      • Produce no flowers or seeds
      • Fossil records date back almost 400 million years, versus 130 million years for flowering plants
  • Brake Family (Pteridaceae)
  • Perennial herb
    • Grows from short creeping rhizomes (horizontal underground stems)
  • Fronds
    • Compound (divided into leaflets), with 2-3 levels of division (2-3 pinnate)
    • Leaflets are round or fan-shaped, slightly lobed, and finely-toothed
    • Stalks (petioles) are dark brown to black, smooth, and wiry
  • Sori 
    • Sori (singular: sorus) are clusters of spore-producing, sac-like structures called sporangia (singular: sporangium)
    • Located in the curled-under margins of the leaflets
    • Have no indusium (plural: indusia), a tissue flap sometimes covering sori
Stems © KKorbholz


  • Native to California
    • Grows in soil and rock crevices on shaded hillsides and in moist woodlands
    • See Calflora for observations of this plant
  • Outside California, grows from Oregon to Baja California, Mexico
  • Grows at elevations to 3,775 ft.

Uses (San Mateo County Parks prohibits removal of any natural material)

  • Native people had a variety of uses for California maidenhair fern
    • Decoction of the plant used for internal pain, purifying blood, and expelling afterbirth (California Ohlone)
    • Stems used to keep pierced ears from closing or as ear decoration (California Pomo)
    • Used roots for binding baskets and stems for basket designs

Name Derivation

  • Adiantum (ad-ee-AN-tum) – from the Greek for “unwettable,” referring to the fronds shedding water
  • jordanii (JOR-dun-ee-eye) – a tribute to Rudolf Jordan, Sr. (1818-1901), a German immigrant to California, who collected this fern and had it identified by German botanist Karl Mueller, who named the species after Jordan
  • Maidenhair – implies fine hairs, which may refer to the slender stems or the many fine roots


  • New fronds grow at the beginning of the wet season and dry up in late fall
  • Host to the fungus-like microorganism Phytophthora ramorum, which causes Sudden Oak Death (SOD)
    • At Edgewood, the 2 species known to be highly susceptible to SOD are coast live oak (Quercus agrifolia var. agrifolia) and Pacific madrone saplings (Arbutus menziesii)
    • For a complete list of known hosts and host associates see USDA Risk Analysis for Phytophthora ramorum, pp.6-9

ID Tips

  • To distinguish from other Edgewood ferns, look for fan-shaped, delicate leaflets

At Edgewood

  • Found in woodlands on moist, shaded hillsides and stream banks

See General References

Specific References

American Fern Society. About Ferns.

Anthropology Museum, California State University, Sacramento. Enduring Traditions: Baskets in Native California, a Mobile Classroom Outreach Trunk.

California Department of Parks and Recreation. 2019. California Indian Baskets.

U.S. Forest Service, United States Department of Agriculture. What Are Ferns?.