Flora of North America species comparison

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Adiantum aleuticum

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

short-creeping or suberect;

scales bronzy deep yellow, concolored, margins entire.
Leaves

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

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

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, 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.
False indusia

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

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

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

Adiantum aleuticum
Phenology Sporulating summer–fall.
Habitat Wooded ravines, shaded banks, talus slopes, serpentine barrens, and coastal headlands (uncommon)
Elevation 0–3200 m [0–10500 ft]
Distribution
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

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.)
Parent taxa Pteridaceae > Adiantum
Sibling taxa
A. capillus-veneris, A. hispidulum, A. jordanii, A. melanoleucum, A. pedatum, A. tenerum, A. tricholepis, A. viridimontanum
Synonyms A. pedatum var. aleuticum, A. boreale, A. pedatum subsp. aleuticum, A. pedatum subsp. calderi, A. pedatum subsp. subpumilum, A. pedatum var. subpumilum
Name authority (Ruprecht) Paris: Rhodora 93: 112. (1991)
Source FNA vol. 2. Treatment author: Cathy A. Paris.
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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