Dryopteris carthusiana

Spinulose Wood Fern

Spinulose Wood Fern, Photo courtesy Wisconsin State Herbarium and Robert Freckmann
Spinulose Wood Fern
Photo courtesy Wisconsin State Herbarium
and Robert Freckmann

Flora, fauna, earth, and sky...
The natural history of the northwoods


  • Dryopteris, from the Greek, drus (drys), "oak" and pteris (pteris), "fern", "fern of the oak wood"
  • carthusiana, after botanist Johan Friedrich Cartheuser (1704-1777).
  • Common name from the spiny pinnules.
  • Other common names include Spreading Wood Fern, Toothed Wood Fern, Narrow Buckler Fern (UK), Dryoptéris des Chartreux, Dryoptère de Cartheuser (Qué), Fougère Spinuleuse, Dryopteris des Chartreux (Fr), Skogsbräken (Swe), Broddtelg (Nor), Smalbladet Mangeløv (Dan), Metsäalvejuuri (Fin), Dornfarn (Ger), Szálkás Pajzsika (Hun)


  • Kingdom Plantae, the Plants
    • Division Polypodiophyta, the True Ferns
      • Class Filicopsida
        • Order Polypodiales
          • Family Dryopteridaceae, the Wood Ferns
            • Genus Dryopteris, the Wood Ferns
  • Taxonomic Serial Number: 502157
  • Also known as Aspidium spinulosum, Dryopteris austriaca var. spinulosa, Dryopteris spinulosa, Polypodium carthusianum, Polypodium spinulosum, Thelypteris spinulosa
  • A tetraploid, sexual fern, thought to have originated from a cross of Dryopteris intermedia and the hypothetical, and presumably extinct, Dryopteris semicristata.


  • A lacy forest fern growing as solitary fronds from a creeping rhizome.
  • Fronds monomorphic, deciduous, 4"-12" × 6"-30".
    • Petiole (leaf stalk) 1/4-1/3 length of leaf, scaly at least at base; scales scattered, ovate, uniformly tan.
    • Blade light green/yellowish green, ovate-lanceolate, and thrice-cut.
    • Pinnae (primary leaflets) more or less in the plane of blade and narrowly triangular; lowest pinnae more broadly triangular and slightly reduced in size.
    • Pinnules (secondary leaflets); the first downward pointing pinnule of the lowest pair of pinnae is noticably longer than the adjacent downward pointing pinnules, and up to twice as long as the first upward pointing pinnule; leaf edges finely spine tipped.
  • Rootstalk ascending to erect.
    • Roots black, wiry, and widely spreading; highly variable.
  • Sori round, midway between midvein and margin of segments.
    • Indusia kidney shaped, lacking glands.


  • Identifiable as a Wood Fern by its larger size, thrice-cut fronds, and woodland habitat.
  • Distinguished from the closely related and nearly identical Intermediate Wood Fern (Dryopteris intermedia) and Spreading Woodfern (Dryopteris expansa), with which it once shared the common species designation of Dryopteris spinulosa, by the first downward pointing secondary leaflet being longer than the downward pointing subleaflet next to it AND that first large downward pointing subleaflet is attached at or very near to the point of attachment of the first upward pointing subleaflet.
  • Field Marks


  • Circumboreal; Alaska to Newfoundland, south to Washington, Idaho, NW Montana, Nebraska, Missouri, Arkansas, Tennessee, and the Carolinas.
  • Also Eurasia; Norway to Russia, south to Eire, Spain, Italy, Greece, and Turkey.


  • Wet woods, moist wooded slopes, stream banks, swamps, and fen carr.






  • By spore and vegetatively by rhizome.


  • By rhizome division.


  • Hardy to USDA Zone 3 (average minimum annual temperature -40ºF)
  • Cultural Requirements
    • Shade to part shade
    • Moist organic soil
  • Available by mail order from specialty suppliers.



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Last Updated on 26 February, 2004