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)
      • Sporangia sacs split open to catapult mature, microscopic spores, which are wind dispersed
    • 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
    • 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)
    • Roots used 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. Resources.

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.

Pai, A. 2018, Dec. 28. Fantastic ferns and where to find them. Bay Nature.

U.S. Forest Service. What are ferns? Forest Service. United States Department of Agriculture.