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• Thelypteridaceae
• Thelypteris
• Thelypteris palustris

Thelypteris palustris — marsh fern

Facts

Marsh fern is the only documented food plant of the marsh fern moth (Fagitana littera) in New England.

Habitat

Anthropogenic (man-made or disturbed habitats), bogs, fens (calcium-rich wetlands), marshes, shores of rivers or lakes, swamps, wetland margins (edges of wetlands)

Characteristics

• Growth form

  Life form

  the plant is herbaceous and terrestrial

  Life stage

  the plant is visible as a typical leaf-bearing fern (sporophyte)

  Spore-bearing leaflets

  the spore-bearing fronds are slightly different from the sterile fronds

• Leaves

  Features of leaves

  there are no special features on the leaves

  Leaf blade length

  10–40 cm

  Leaf blade shape

  the leaf blades are widest above the base, then taper narrowly towards the tip (lanceolate)

  Leaf blade tip shape

  the tip of the leaf blade is a blunt point (obtuse)

  Leaf blade width

  At least 15 cm

  Leaf divisions

  • the leaf blade is compound (divided into leaflets)
  • the leaf blade is twice compound (divided into leaflets, which are further divided into leaflets)

  Leaf lifespan

  the leaves drop off in winter

  Leaf stalk color

  yellow to brown

  Leaf stalk hairs

  • the leaf stalk has hairs
  • there are no hairs on the leaf stalk

  Leaf stalk length

  90–600 mm

  Leaf stalk relative length

  • the leaf stalk is more than a quarter, but less than three quarters as long as the blade
  • the leaf stalk is more than three quarters as long as the blade

  Leaf stalk scale location

  • the scales are present on both the lower and upper halves of the leaf stalk
  • the scales are present only on the lower half of the leaf stalk
  • there are no scales on the leaf stalk

  Leaf stalk scales

  • the leaf stalk has scales
  • there are no scales on the leaf stalk

  Leaf stalk vessels

  2 bundles

  Leaf vein branching

  the secondary veins of the leaf blade branch dichotomously (two equal branches at each branch point)

  Leaf vein tips

  the veins go all the way to the edge of the leaf blade

  Leaflet relative size

  the bottom leaflets are about half as long as, to slightly longer than, the leaflets from the middle of the frond

  Leaflet stalks

  • the leaflets are stalked
  • the leaflets do not have stalks

  Lobe or leaflet length

  20–100 mm

  Lobe or leaflet pairs

  Up to 8

  Lobe or leaflet shape

  the lobe or leaflet is rectangular but with rounded ends (oblong)

  Lobe or leaflet width

  5–20 mm

  Plant growth form

  the leaves grow from a rhizome growing at or below the ground

  final leaf segment margin

  the topmost lobe or leaflet of the leaf blade has a smooth or lobed edge

• Place

  Habitat

  wetlands

  New England state

  • Connecticut
  • Maine
  • Massachusetts
  • New Hampshire
  • Rhode Island
  • Vermont

  Specific habitat

  • bogs
  • edges of wetlands
  • fens (calcium-rich wetlands)
  • man-made or disturbed habitats
  • marshes
  • shores of rivers or lakes
  • swamps

• Spores or spore cones

  Sorus features

  there are no special features on the sorus

  Sorus shape

  • the sori are circular or kidney-shaped
  • there are no sori, or they are concealed in leaf segments or hardened, capsule-like structures derived from a modified leaflet

  Sporangia location

  the spores are clustered on sori on the lower surface of the leaf blade

  Sporangium type

  the sporangia are opaque without an annulus and usually without a stalk (leptosporangiate)

  Spore forms

  there is only one type of spore present

Wetland status

Usually occurs in wetlands, but occasionally in non-wetlands. (Wetland indicator code: FACW)

New England distribution and conservation status

From the dichotomous key of Flora Novae Angliae