Adiantum pedatum |
Adiantum |
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adiante du Canada, five-fingered fern, northern maidenhair, northern maidenhair fern |
maidenhair fern |
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Habit | Plants terrestrial or on rock. | |||||||||||||||||||||||||||||||||||||
Stems | short-creeping; scales bronzy deep yellow, concolored, margins entire. |
short- to long-creeping or suberect, branched; scales deep tawny yellow to dark reddish brown [black], concolored or bicolored, linear-lanceolate to lanceolate, margins entire, erose-ciliate, or minutely dentate. |
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Leaves | lax-arching (rarely pendent), closely spaced, 40–75 cm. |
monomorphic to somewhat dimorphic, densely clustered to closely spaced [distant], 15–110 cm. |
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Petiole | 1–2 mm diam., glabrous, occasionally glaucous. |
chestnut brown to dark purple or blackish, with single groove adaxially, glabrous, hispid, or strigose, with 1 or 2 vascular bundles. |
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Blade | fan-shaped, pseudopedate, 1-pinnate distally, 15–30 × 15–35 cm, glabrous; proximal pinnae 3–9-pinnate; rachis straight, glabrous, occasionally glaucous. |
lanceolate, ovate, trowel-shaped, or fan-shaped, 1–4(–9)-pinnate proximally, membranaceous to papery, both surfaces commonly glabrous (2 species with scattered hairs), adaxially dull or shiny, not striate; rachis straight or flexuous. |
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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. |
subsessile to short-stalked (stalks terminating in cupulelike swelling at base of pinna in A. tenerum), round, fan-shaped, rhombic, or oblong, 3–29 mm wide; base truncate to cuneate, free from costa; stalk dark, often lustrous; fertile segments with marginal lobes recurved to form false indusia. |
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Veins | of ultimate segments conspicuous, free, ± dichotomously forking near base and well above segment base [anastomosing in a few tropical species], parallel distally. |
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Indusia | transversely oblong, 1–3 mm, glabrous. |
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False indusia | light gray-green or brown to dark brown, narrow, 0.6–1 mm wide, marginal, concealing sporangia until sporangia dehisce. |
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Sporangia | submarginal, borne along or sometimes also between veins on abaxial surface of false indusium, paraphyses and glands absent. |
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Spores | mostly 34–40 µm diam. 2n = 58. |
yellow or yellowish brown, tetrahedral-globose, trilete, rugulate to rugose or tuberculate, equatorial ridge absent. |
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Segment | stalks 0.5–1.5(–1.7) mm, dark color entering into segment base. |
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x | = 29, 30. |
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Adiantum pedatum |
Adiantum |
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Phenology | Sporulating summer–fall. | |||||||||||||||||||||||||||||||||||||
Habitat | Rich, deciduous woodlands, often on humus-covered talus slopes and moist lime soils | |||||||||||||||||||||||||||||||||||||
Elevation | 0–700 m (0–2300 ft) | |||||||||||||||||||||||||||||||||||||
Distribution |
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
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Nearly worldwide except at latitudes greater than 60° |
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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.) |
Most diverse in Andean South America, Adiantum is primarily a tropical genus; of the nine species occurring in the flora, A. melanoleucum, A. tenerum, and A. tricholepis are strictly subtropical. Adiantum hispidulum occurs only as an escape from cultivation. The genus is absent from dry areas in the interior of the continent. Adiantum is a very clearly circumscribed genus of ferns, the character state "sporangia borne on abaxial surface of false indusium" being both necessary and sufficient to define it. Within this large and widespread genus, however, species relationships are mostly unknown. An evolutionary classification of the group is indeed much needed (R. M. Tryon and A. F. Tryon 1982). Species ca. 150–200 (9 in the flora). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Key |
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Source | FNA vol. 2. | FNA vol. 2. | ||||||||||||||||||||||||||||||||||||
Parent taxa | Pteridaceae > Adiantum | Pteridaceae | ||||||||||||||||||||||||||||||||||||
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Synonyms | A. pedatum, A. pedatum | |||||||||||||||||||||||||||||||||||||
Name authority | Linnaeus: Sp. Pl. 2: 1095. (1753) | Linnaeus: Sp. Pl. 2: 1094. 1753; Gen. Pl. ed 5, 485. (1754) | ||||||||||||||||||||||||||||||||||||
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