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Adiantum aleuticum — western maidenhair fern

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Facts

Western maidenhair fern is mainly found in western North America, from southern Arizona to the Aleutian Islands. There are a few disjunt populations in the East. In New England it is a rare fern of serpentine cliffs and talus in Maine and Vermont.

Habitat

Cliffs, balds, or ledges, ridges or ledges, 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
  • Maine
  • 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
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
there are no sori, or they are concealed in leaf segments or hardened, capsule-like structures derived from a modified leaflet
Leaf stalk scales
there are no scales on the leaf stalk
Leaf stalk hairs
there are no hairs on the leaf stalk
Leaf blade length
5–45 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
    the petiole (leaf stalk or stipe) appears to fork into two equal halves
    Leaf blade length
    5–45 cm
    Leaf blade shape
    • the leaf blades are funnel-shaped
    • the leaf blades are roughly fan-shaped
    Leaf blade tip shape
    the tip of the leaf blade is a sharp point (acute)
    Leaf blade width
    At least 5 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
    Leaf lifespan
    the leaves drop off in winter
    Leaf stalk color
    red or red-brown to purple or black
    Leaf stalk hairs
    there are no hairs on the leaf stalk
    Leaf stalk scale location
    there are no scales on the leaf stalk
    Leaf stalk scales
    there are no scales on the leaf stalk
    Leaf stalk vessels
    1 bundle, U-shaped
    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
    NA
    Leaflet stalks
    the leaflets are stalked
    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
    terrestrial
    New England state
    • Maine
    • Vermont
    Specific habitat
    • cliffs, balds, or ledges
    • ridges or ledges
    • talus or rocky slopes

  • Spores or spore cones

    Sorus features
    there are no special features on the sorus
    Sorus shape
    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 hidden inside hardened, rolled-under leaf segments
    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
absent
Maine
present
Massachusetts
absent
New Hampshire
absent
Rhode Island
absent
Vermont
present

Conservation status

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

Maine
extremely rare (S-rank: S1), endangered (code: E)
Vermont
extremely rare (S-rank: S1)

From Flora Novae Angliae dichotomous key

1.  Adiantum aleuticum (Rupr.) Paris NC

western maidenhair fern. Adiantum pedatum L. ssp. aleuticum (Rupr.) Calder & Taylor; 
 A. pedatum L. var. aleuticum Rupr.;  A. pedatum L. ssp. calderi Cody • ME, VT. Serpentine 
cliffs and talus.

Native to North America?

Yes

Sometimes confused with

Adiantum viridimontanum:
ultimate leaf segments on stalks longer than 0.9 mm and false indusial 2-5 (rarely to 10) mm long (vs. A. aleuticum, with ultimate leaf segments on stalks 0.3-1.3 mm long and false indusial 0.8-2.9 (rarely to 3.4) mm long).

Synonyms

  • Adiantum pedatum ssp. aleuticum (Rupr.) Calder & Taylor
  • Adiantum pedatum ssp. calderi Cody
  • Adiantum pedatum var. aleuticum Rupr.

Family

Pteridaceae

Genus

Adiantum