Equisetum sylvaticum

Wood Horsetail

Wood Horsetail, Photo copyright Earl J.S. Rook
Wood Horsetail
Photo © Earl J.S. Rook

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The natural history of the northwoods


Name:

  • Equisetum, from the Latin, equus, "horse", and seta, "bristle, animal hair"
  • sylvaticum, from the Latin, sylva, "woods, forest", and aticus "habitat"; hence "growing in the woods, wild"
  • Wood Horsetail, from its preferred habitat
  • Other common names include: Sylvan Horsetail, Woodland Horsetail, Prêle des Bois (Qué), Skogsfräken (Swe), Skogsnelle (Nor), Skov-Padderok (Dan), Metsäkorte (Fin), Skogelfting (Is), Wald-Schachtelhalm (Ger), Erdei Zsurló (Hun)

Taxonomy:

    • Kingdom Plantae, the Plants
    • Division Equisetophyta, the Horsetails
      • Class Equisetopsida, the Horsetails
        • Order Equisetales, the Horsetails
          • Family Equisetaceae, the Horsetails
            • Genus Equisetum, the Horsetails
  • Taxonomic Serial Number: 17161
  • Also known as Equisetum capillare

Description:

  • A heavily branched, flat topped horsetail of wet places.
  • Stems dimorphic, annual, erect.
    • Sterile stem green, densely branched from the nodes, about 18" tall, with 10-18 surface ridges, the ridges usually with silica spicules; central hollow usually more than ½ the stem diameter; inter- nodes about 1½" long 1.5-3 mm in diameter; main stem sheaths 5-10 mm long, the teeth coherent in usually 3-5 broad lobes, reddish-brown, 3-5 mm long.
    • Fertile stem initially unbranched and lacking chlorophyl; becoming green and branched after spores are released and the cone withers and falls away. Though looking very much like the sterile stems at this point, they remain somewhat smaller but with larger sheaths (Measurements other than height generally exceed those of the sterile stems) Leaf sheaths 10-25 mm long, the teeth fused into reddish-brown lobes 4-15 mm long.
  • Branches rebranched, delicate, arching, spreading to recurved, 4-5 angled, in regular whorls, the first internode longer than the subtending stem sheath, 5-9 mm long. Teeth narrow, pointed, spreading.
  • Rhizomes shiny, light brown, smooth, covered with hairs, occasionally bearing tubers. The extensive, creeping rhizomes may outweigh above ground growth by a ratio of 100 to 1.
  • Cone ¾"-1", borne on short stalk at tip of fertile stem [Photo Link]

Identification:

  • Identifiable as Horsetail by the upright, hollow, jointed, cylindrical stems with inconsequential and easily overlooked leaves.
  • Distinguished from our other Horsetails by the elegant whorls of slender, recurved branches, generally twelve or more branches to a whorl, which are very about 5 inches long, quadrangular and beset by several secondary whorls so that the plant resembles a miniature pine tree.
  • Field Marks
    • compond branching; our only Horsetail in which the branches commonly and regularly re-branch
    • leaf sheaths; our only Horsetail with reddish brown sheaths

Distribution:

  • Circumboreal, in North America south to Washington, northern Idaho, northwestern Montana, South Dakota, Nebraska, Iowa, Ohio, Kentucky, and Virginia.
  • Eurasia south to the Mediterranean, the Balkans, the Crimea, and the Caspian region, across Siberia to Manchuria, Korea, and Hokkaido.

Habitat:

  • Lowland wet conifer forests, also common in mixed upland, dry conifer, and deciduous forest habitats.
  • Moist open woods, bogs, swamps, prairies, meadows, stream banks.
  • An indicator of boreal and cool-temperate climates, and very moist to wet, nitrogen-poor soils.
  • Present in appropriate habitat through all successional stages to climax forest.

Fire:

  • Aboveground stems of killed by fire.
  • Survives repeated fires thanks to deeply buried, nearly indestructible rhizomes, which penetrate well into mineral soil or clay, allowing rapid revegetation even after severe fire.
  • Invades recently burned areas in any stage of succession; colonizing new burns through wind-dispersed spores.

Associates:

History:

Uses:

  • Poisonous to humans and livestock

Reproduction:

  • Reproduces by spores and vegetatively by rhizomes
  • Primarily reproduces by vegetative means; the majority of shoots arise from rhizomes. Rhizome systems are extensive, deeply buried, and extremely long-lived (perhaps several thousand years old).

Propagation:

  • By rhizome division

Cultivation:

  • The most attractive of the native Horsetails because of its lacy appearance
  • Hardy to USDA Zone 3 (average minimum annual temperature -40ºF)
  • Cultural Requirements
    • Shade to partial shade
    • Soil moist to wet, slightly acidic
    • Fertilization detrimental
  • Good for naturalizing wet, woodland areas
  • Available by mail order from specialty suppliers.

Links:

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Last Updated on 26 February, 2004