Flora of North America species comparison

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Adiantum pedatum

Adiantum aleuticum

adiante du Canada, five-fingered fern, northern maidenhair, northern maidenhair fern

adiante des aléoutiennes, Aleutian maidenhair, five-finger fern, maidenhair fern, northern maiden-hair, northern maidenhair fern, western maidenhair, western maidenhair fern
Stems

short-creeping;

scales bronzy deep yellow, concolored, margins entire.

short-creeping or suberect;

scales bronzy deep yellow, concolored, margins entire.
Leaves

lax-arching (rarely pendent), closely spaced, 40–75 cm.

lax-arching to stiffly erect or pendent, often densely clustered, 15–110 cm.
Petiole

1–2 mm diam., glabrous, occasionally glaucous.

0.5–3 mm diam., glabrous, often glaucous.
Blade

fan-shaped, pseudopedate, 1-pinnate distally, 15–30 × 15–35 cm, glabrous;

proximal pinnae 3–9-pinnate;

rachis straight, glabrous, occasionally glaucous.

fan-shaped to funnel-shaped, pseudopedate, 1-pinnate distally, 5–45 × 5–45 cm;

proximal pinnae (1–)2–7-pinnate;

rachis straight, glabrous, often with glaucous bloom.
Ultimate segments

oblong, ca. 3 times as long as broad;

basiscopic margin straight;

acroscopic margin lobed, lobes separated by narrow incisions 0–0.9(–1.1) mm wide;

apex obtuse, divided into shallow, rounded lobes separated by shallow sinuses 0.1–2(–3.7) mm deep, margins of lobes crenulate or crenate-denticulate.

oblong, long-triangular, or occasionally reniform, ca. 2.5–4 times as long as broad;

basiscopic margin straight to oblique, or occasionally excavate;

acroscopic margin lobed, lobes separated by narrow to broad incisions 0.2–3 mm wide;

apex acute to obtuse, obtuse apices divided into ± angular lobes separated by sinuses 0.6–4 mm deep, margins of lobes sharply denticulate.
Indusia

transversely oblong, 1–3 mm, glabrous.

False indusia

transversely oblong to crescent-shaped, 0.2–3.5(–6) mm, glabrous.
Spores

mostly 34–40 µm diam. 2n = 58.

mostly 37–47 µm diam. 2n = 58.
Segment

stalks 0.5–1.5(–1.7) mm, dark color entering into segment base.

stalks 0.2–0.9(–1.3) mm, dark color entering into segment base or not.

Adiantum pedatum

Adiantum aleuticum
Phenology Sporulating summer–fall. Sporulating summer–fall.
Habitat Rich, deciduous woodlands, often on humus-covered talus slopes and moist lime soils Wooded ravines, shaded banks, talus slopes, serpentine barrens, and coastal headlands (uncommon)
Elevation 0–700 m (0–2300 ft) 0–3200 m (0–10500 ft)
Distribution
from FNA
AL; AR; CT; DC; DE; GA; IA; IL; IN; KS; KY; LA; MA; MD; ME; MI; MN; MO; MS; NC; NE; NH; NJ; NY; OH; OK; PA; RI; SC; TN; VA; VT; WI; WV; NB; NS; ON; QC
[WildflowerSearch map]
[BONAP county map]
from FNA
AK; AZ; CA; CO; ID; MD; ME; MT; NV; OR; PA; UT; VT; WA; WY; AB; BC; NF; QC; Mexico in Chihuahua
[WildflowerSearch map]
[BONAP county map]
Discussion

Once considered a single species across its range in North America and eastern Asia, Adiantum pedatum is considered to be a complex of at least three vicariant species (A. pedatum and A. aleuticum occur in North America) and a derivative allopolyploid species (C. A. Paris 1991). Adiantum pedatum in the strict sense is restricted to deciduous woodlands in eastern North America.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Adiantum aleuticum is disjunct in wet rock fissures at high elevations in Arizona, Colorado, Montana, Nevada, Utah, Wyoming, and Mexico in Chihuahua, and it is disjunct on serpentine in Newfoundland, Quebec, Maine, Maryland, Pennsylvania, and Vermont.

Although the western maidenhair has traditionally been interpreted as an infraspecific variant of Adiantum pedatum, the two taxa are reproductively isolated and differ in an array of morphologic characteristics. Therefore, they are more appropriately considered separate species (C. A. Paris and M. D. Windham 1988). Morphologic differences between A. pedatum and A. aleuticum are subtle; the two may be separated, however, using characteristics in the key. Adiantum aleuticum occurs in a variety of habitats throughout its range, from moist, wooded ravines to stark serpentine barrens and from coastal cliffs to subalpine boulder fields. Although morphologic differences exist among populations in these diverse habitats, they are not consistent. Consequently, infraspecific taxa are not recognized here within A. aleuticum.

(Discussion copyrighted by Flora of North America; reprinted with permission.)
Source FNA vol. 2. FNA vol. 2.
Parent taxa Pteridaceae > Adiantum Pteridaceae > Adiantum
Sibling taxa
A. aleuticum, A. capillus-veneris, A. hispidulum, A. jordanii, A. melanoleucum, A. tenerum, A. tricholepis, A. viridimontanum
A. capillus-veneris, A. hispidulum, A. jordanii, A. melanoleucum, A. pedatum, A. tenerum, A. tricholepis, A. viridimontanum
Synonyms A. pedatum, A. pedatum A. pedatum var. aleuticum, A. boreale, A. pedatum subsp. aleuticum, A. pedatum subsp. calderi, A. pedatum subsp. subpumilum, A. pedatum var. subpumilum
Name authority Linnaeus: Sp. Pl. 2: 1095. (1753) (Ruprecht) Paris: Rhodora 93: 112. (1991)
Web links 
Unless otherwise noted, all data comes from the online version of the Flora of North America, who have made most of their content available via a Creative Commons license (CC BY 4.0).



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