Goldback Fern

Goldback Fern © DSchiel

Pentagramma triangularis
NATIVE

Description (Jepson, PlantID.net)

  • Fern (Polypodiopsida) 
    • Ferns are a 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 primarily from rhizomes (horizontal underground stems)
  • Fronds
    • Triangular blades are compound (divided into leaflets), with usually 2 (sometimes 3) levels of division (2-3 pinnate)
    • Light yellow exudate (an excreted substance) on underside of leaflets 
    • Stalks (petioles) are brown to black, smooth and wiry
  • Sori 
    • Sori (singular: sorus) are clusters of spore-producing, sac-like structures called sporangia (singular: sporangium)
    • Located on the underside of leaflets
    • Have no indusium (plural: indusia), a tissue flap sometimes covering sori

Distribution

  • Native to California
    • Grows in shady, rocky areas in chaparral, oak woodlands, and mixed-evergreen forests
    • See Calflora for statewide observations of this plant
  • Outside California, grows from British Columbia to Baja California, Mexico, and east to Idaho, Nevada, and Utah
  • Grows at elevations to 7,500 ft.
Underside with Exudate and Spores © DSchiel

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

  • Dusky-footed woodrats (Neotoma fuscipes annectens) eat the fronds
  • Native people had several uses for goldback fern
    • Stems used in basketry (Mason 1904)
    • Plant used to ease childbirth afterpains and for toothaches
    • Spores used by children to make designs on their hands

Name Derivation

  • Pentagramma (pen-ta-GRAM-ma) – from the Latin for “five lines” or “stripes”: a pentagram can be drawn from the tips of the fronds
  • triangularis (try-ang-gew-LARE-is) – from the Latin for “three sided,” referring to the general shape of the fronds
  • Goldback – refers to the light yellow color on the back of the fern created by the powdery exudate

Notes

  • The light yellow powdery substance on the underside of the fronds is not spores, but a protective covering to inhibit dehydration
Curled Frond © DSchiel

ID Tips

  • To distinguish goldback ferns from other Edgewood ferns, turn over the frond to see the light yellow powder (dry exudate), which will come off easily on fingers or clothing; the darker, gold-colored features are spores
  • During the dry season, frond curls up; as soon as moisture is available, it uncurls

At Edgewood

  • Found in woodlands
    • On every trail except the Sunset Trail
    • See iNaturalist for observations of this plant
  • Grows new fronds when wet weather arrives, but may keep fronds all year

See General References

Specific References

American Fern Society. About Ferns.

Mason, O.T. 1904. Indian Basketry: Studies in a Textile Art Without Machinery, Volume 2. Doubleday, Page, and Co.

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