Thelypteris palustris

Marsh Fern

Marsh Fern, Photo courtesy Wisconsin State Herbarium and Robert Freckmann
Marsh Fern
Photo courtesy Wisconsin State Herbarium
and Robert Freckmann

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


  • Thelypteris, from the Greek, qelus (thelus), "female", and pteris (pteris), "fern"
  • palustris, from the Latin, "fenny, marshy, swampy"
  • Common Name, from its preferred habitat
  • Other common names include Eastern Marsh Fern, Meadow Fern, thélyptère des marais (Qué), Kärrbräken (Swe), Myrtelg (Nor), Kær-Dunbregne (Dan), Nevaimarre (Fin), Sumpffarn (Ger), Raineach Lèana (Gaelic), Harilik Soosõnajalg, Sõnajalg, Soosõnajalg (Estonia), Tõzegpáfrány (Hun)


  • Kingdom Plantae, the Plants
    • Division Polypodiophyta, the True Ferns
      • Class Filicopsida
        • Order Polypodiales
          • Family Thelypteridaceae, the Marsh Ferns
            • Genus Thelypteris, the Lady Ferns
  • Taxonomic Serial Number: 17251
  • Also known as Acrostichum thelypteris, Dryopteris thelypteris, Lastrea thelypteris, Thelypteris confluens var. pubescens , Thelypteris thelypteroides
  • Varieties
    • Thelypteris palustris var. palustris occurs in Eurasia.
    • Thelypteris palustris var. pubescens occurs in Eastern North America.


  • A common wetland fern; each frond arising individually from a creeping rhizome without forming clumps.
  • Fronds monomorphic or slightly dimorphic, deciduous; fertile leaves more erect, narrower, with leaf edges slightly rolled over spore-bearing sori, 9"-36" tall.
    • Petiole (leaf stalk) smooth and pale green above, black at base, sparsely set with smooth, tan, ovate scales, 3½"-18". Petioles of fertile fronds much longer than those of sterile.
    • Blade lanceolate, 4"-16", lowest pinnae commonly somewhat shorter, blade tapering gradually to lobed tip.
    • Rachis (axis) green, slender, smooth.
    • Pinnae (leaflets) deeply cut to within 1mm of rib; lobes oblong, with smooth edge. About a dozen per frond, they are all perpendicular to the stem.
  • Rootstalk long-creeping, slender (1mm-3mm), black.
    • Roots black, wiry, creeping, and shallow; typically few in number.
  • Sori round, on underside of fronds near the midvein
    • indusia tan, often hairy
    • sporangia glabrous


  • Identifiable by wetland habitat and frond characteristics.
  • Distinguished from the closely related Long Beech Fern (Phegopteris connectilis), by its lowest leaflets growing perpendicular to the stem.
  • Field Marks
    • marshy habitat
    • fronds emerge singly from horizontal rhizome as scattered fronds, no clumps
    • leafstalk longer than most of our ferns, with black at base
    • frond widest near base; all leaflets perpendicular to stem
    • 1½ times divided into tiny, more or less toothless lobes with forking veins.


  • Manitoba to Newfoundland, south to Texas, Louisiana, Mississippi, Alabama, Georgia, and Florida.
  • Bermuda, Cuba, Peru; perhaps Mexico.
  • Norway to Russia, south to Iberia, France, Italy, Greece, and the Ukraine.
  • Armenia, Georgia, Japan, Kazakhstan, Kyrgyzstan, Russia, Tajikistan, Turkmenistan


  • Swamps, bogs, wet meadows, wet woods, and marshes, also along riverbanks and roadside ditches.
  • Usually in rich, wet soil but not in standing water
  • .






  • By spore and vegetatively by rhizome


  • By spore or rhizome division


  • Hardy to USDA Zone 3 (average minimum annual temperature -40ºF)
  • Cultural Requirements
    • Sun or shade
    • Soil slightly acidic, pH 5-7
    • Standing water to moist soil
  • Can become invasive.
  • Available by mail order from specialty suppliers.



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Last Updated on 26 February, 2004