Goldback Fern :

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)
  - Sporangia sacs split open to catapult mature, microscopic spores, which are wind dispersed
- 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.

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

Wildlife
- Fronds eaten by Dusky-footed woodrats (Neotoma fuscipes annectens)
Native people
- 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
Watch this short video showing fern reproduction in action (KQED 2024)

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

Specific References

American Fern Society. About Ferns.

KQED San Francisco. 2024, April 16. Watch ferns get freaky [Video]. Deep Look. YouTube.

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

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

General References

Calflora Database. 2014. Berkeley, California.

Calscape. 2018. California Native Plant Society.

Corelli, T. 2004. Flowering Plants of Edgewood Natural Preserve (2nd. ed.). Monocot Press, Half Moon Bay, California.

Elpel, T.J. 2013. Botany in a Day: The Patterns Method of Plant Identification. HOPS Press, Pony, Montana.

Harris, J.G., and M.W. Harris. 2013. Plant Identification Terminology: An Illustrated Glossary. Spring Lake Publishing, Spring Lake, Utah.

Keator, G. 2009. California Plant Families. University of California Press, Berkeley and Los Angeles, California.

Regents of the University of California. Jepson eFlora. Jepson Herbarium. University of California, Berkeley.