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• Cystopteris fragilis

Cystopteris fragilis — fragile fern

Facts

Fragile fern is more likely to be found on cliffs and at higher elevations and/or latitudes than the other fragile fern (Cystopteris) species. The stem is brittle near its base. If you think you have found this species, look for the previous year's remaining bases of broken off leaves.

Habitat

Talus and rocky slopes

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 similar in size and shape to the sterile fronds

• Leaves

  Features of leaves

  there are no special features on the leaves

  Leaf blade length

  5–30 cm

  Leaf blade shape

  • the leaf blades are widest above the base, then taper narrowly towards the tip (lanceolate)
  • the leaf blades are widest near the middle and tapered towards the base and tip (elliptic)

  Leaf blade width

  At least 3 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

  there are no hairs on the leaf stalk

  Leaf stalk length

  26–229 mm

  Leaf stalk relative length

  the leaf stalk is more than three quarters as long as the blade

  Leaf stalk scale location

  the scales are present only on the lower half of the leaf stalk

  Leaf stalk scales

  the leaf stalk has scales

  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

  9–65 mm

  Lobe or leaflet pairs

  9–15

  Lobe or leaflet shape

  • the lobe or leaflet is roughly triangular with the stalk in the center of the narrowest side (narrow-triangular)
  • the lobe or leaflet is roughly triangular with the stalk in the center of the widest side (broad-triangular)
  • the lobe or leaflet is widest below the middle and broadly tapering at both ends; egg-shaped

  Lobe or leaflet width

  5–25 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
  • the topmost lobe or leaflet of the leaf blade has an edge with teeth

• Place

  Habitat

  terrestrial

  New England state

  • Connecticut
  • Maine
  • Massachusetts
  • New Hampshire
  • Vermont

  Specific habitat

  talus or rocky slopes

• Spores or spore cones

  Sorus features

  there are no special features on the sorus

  Sorus shape

  the sori are circular or kidney-shaped

  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 non-wetlands, but occasionally in wetlands. (Wetland indicator code: FACU)

New England distribution and conservation status

From the dichotomous key of Flora Novae Angliae