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


  • 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

See General References

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.

Browse Edgewood Plants in this Family