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Gymnocarpium dryopteris — northern oak fern

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Facts

Northern oak fern produces new fronds all summer long. The Cree Indians crushed oak fern leaves to repel mosquitoes and to treat bites.

Habitat

Cliffs, balds, or ledges, forests, talus and rocky slopes

New England distribution

Adapted from BONAP data

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North America distribution

Adapted from BONAP data

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Characteristics

Habitat
terrestrial
New England state
  • Connecticut
  • Maine
  • Massachusetts
  • New Hampshire
  • Rhode Island
  • Vermont
Leaf divisions
  • the leaf blade is three times compound (divided into leaflets, which are further divided into leaflets, which are further divided into leaflets), or more
  • the leaf blade is twice compound (divided into leaflets, which are further divided into leaflets)
Plant growth form
the leaves grow from a rhizome growing at or below the ground
Spore-bearing leaflets
the spore-bearing fronds are similar in size and shape to the sterile fronds
Sorus shape
the sori are circular or kidney-shaped
Leaf stalk scales
the leaf stalk has scales
Leaf stalk hairs
the leaf stalk has hairs
Leaf blade length
7–20 cm
Leaf vein tips
the veins go all the way to the edge of the leaf blade
Show all 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
    7–20 cm
    Leaf blade shape
    the leaf blades are roughly triangular
    Leaf blade tip shape
    the tip of the leaf blade is rounded
    Leaf blade width
    At least 10 cm
    Leaf divisions
    • the leaf blade is three times compound (divided into leaflets, which are further divided into leaflets, which are further divided into leaflets), or more
    • 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
    • green
    • yellow to brown
    Leaf stalk hairs
    the leaf stalk has hairs
    Leaf stalk length
    90–280 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 are not branched
    Leaf vein tips
    the veins go all the way to the edge of the leaf blade
    Leaflet relative size
    the bottom leaflets are at least one and a half times as long as the leaflets from the middle of the frond
    Leaflet stalks
    • the leaflets are stalked
    • the leaflets do not have stalks
    Lobe or leaflet length
    20–120 mm
    Lobe or leaflet pairs
    5–15
    Lobe or leaflet shape
    the lobe or leaflet is rectangular but with rounded ends (oblong)
    Lobe or leaflet width
    38–120 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
    • Rhode Island
    • Vermont
    Specific habitat
    • cliffs, balds, or ledges
    • forests
    • 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)

In New England

Distribution

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

Conservation status

Exact status definitions can vary from state to state. For details, please check with your state.

Maine
unranked (S-rank: SNR)
Massachusetts
widespread (S-rank: S5)
Rhode Island
extremely rare (S-rank: S1), state threatened (code: ST)

From Flora Novae Angliae dichotomous key

1.  Gymnocarpium dryopteris (L.) Newman N

northern oak fern. Carpogymnia dryopteris (L.) A. & D. Löve; Dryopteris dryopteris (L.) Britt.; Polypodium dryopteris L. • CT, MA, ME, NH, RI, VT. Forests, base of cliffs, talus slopes.

1×G. disjunctum (Rupr.) Ching. Gymnocarpium ×‌brittonianum (Sarvela) Pryer & Haufler is a rare oak fern hybrid known from CT, MA, ME, NH, VT. Morphologically it most closely resembles G. disjunctum, with the first pair of leafules of the second pair of leaflets markedly unequal in length (the basiscopic leafules much longer than the acroscopic leafules; those of G. dryopteris are usually ± equal or the basiscopic leafules slightly longer). Spore morphology is an important character for diagnosing this hybrid. Both round and abortive spores are present. Distribution of this nothospecies is based on Pryer and Haufler (1993). Given that G. disjunctum is restricted to northwestern North America, it is plausible that plants seen with dimorphic spores are the result of a different hybrid combination or a separate phenomenon altogether.

Native to North America?

Yes

Sometimes confused with

Gymnocarpium jessoense:
leaf stipitate-glandular on petiole, rachis, and abaxial blade surface, and basal leaflets and basiscopic leafules curving toward apex of plant (vs. G. dryopteris, with the leaf essentially glabrous, and basal leaflets and basiscopic leafules spreading, not curving toward plant apex).

Synonyms

  • Carpogymnia dryopteris (L.) A. & D. Löve
  • Dryopteris dryopteris (L.) Britt.
  • Polypodium dryopteris L.

Family

Woodsiaceae

Genus

Gymnocarpium