Horsetail Family :

Equisetaceae (ek-wi-see-TA-see-ee)

Iconic Features

Spore-bearing ferns
Hollow, jointed stems
Whorled, scale-like leaves

Description (Jepson)

Ferns (Polypodiopsida)
- An early group of vascular plants that produce spores (reproductive cells)
  - Do not produce flowers or seeds
  - Fossil records date back almost 400 million years, versus 130 million years for flowering plants
Perennial herbs
- Grow from rhizomes (horizontal underground stems)
Stems
- Ribbed and hollow, except at joints (nodes)
- Some species with whorls of solid, grooved branches
- With both sterile and fertile stems
  - Sterile vegetative stems
    - Green and photosynthetic
  - Fertile stems
    - Brown, not photosynthetic, and fleshy
    - Cone-like structure (strobilus) of spores at tip
Leaves
- Extremely small and scale-like
  - Whorled and fused into a freely-toothed sheath, appressed to the stem nodes
- Usually not photosynthetic
Sporangia
- Spores are produced by sac-like structures called sporangia (singular: sporangium)
- Found on the inner surface of umbrella-like scales on the terminal, cone-like structures of fertile stems

Notes

Family consists of 1 genus of 15 species
- Found worldwide except in Australia and New Zealand
Scientific name from the Latin equus, “horse,” and seta, “bristle,” referring to the stems of some species appearing like the tail of a horse
Sole-surviving family of a plant order with many tree-sized fossils (Feng 2017)
- Horsetails are often referred to as “living fossils,” which for more than 100 million years were a diverse and dominant part of understory vegetation in late Paleozoic forests (c. 419 million to 252 million years ago)
- Extinct branching tree ferns, called Calamites, grew to 65 ft. tall
  - Calamites are major components of coal deposits
Giant horsetail (Equisetum telmateia ssp. braunii) is the only member of this family found at Edgewood
DNA studies have shown that horsetails are more closely related to “true ferns” than to the “fern allies” (Lycophytes, e.g. club mosses, spike mosses, and quillworts) in which they were traditional grouped
Edgewood has 7 fern species in 4 plant families
- Brake family (Pteridaceae)
  - California maidenhair fern (Adiantum jordanii)
  - Coffee fern (Pellaea andromedifolia)
  - Goldback fern (Pentagramma triangularis)
- Polypody family (Polypodiaceae)
  - California polypody (Polypodium californicum)
- Wood fern family (Dryopteridaceae)
  - Coastal wood fern (Dryopteris arguta)
  - Western sword fern (Polystichum munitum)
- Horsetail family (Equisetaceae)
  - Giant horsetail (Equisetum telmateia ssp. braunii)

Specific References

Feng, Z. 2017. Late Palaeozoic plants. Current Biology 27: R905-R909. Science Direct.

Gill, V. 2013, Sep. 11. Horsetail plant spores use ‘legs’ to walk and jump. Science. BBC News.

Husby, C. 2003. The giant horsetails. Florida International University.

Pinson, J. 2020-21. About ferns. American Fern Society.

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.

Charters, M.L. 2015. California Plant Names: Latin and Greek Meanings and Derivations.

Charters, M.L. 2017. Southern California Wildflowers: Guide to the Pronunciation of Specific, Generic and Family Names.

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.

Flora of North America. efloras.org.

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.

Native American Ethnobotany DB.

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

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