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black maidenhair fern, common maidenhair, southern maiden-hair, southern maidenhair fern, Venus hair, Venus hair fern, Venus's-hair fern

brittle maidenhair, fan maidenhair



scales golden brown to medium brown, concolored, iridescent, margins entire or occasionally with single broad tooth near base.


scales bicolored, centers dark reddish brown, margins pale tan, erose-ciliate.


lax-arching or pendent, closely spaced, 15–75 cm.

arching or sometimes pendent, closely spaced, 20–110 cm.


0.5–1.5 mm diam., glabrous, occasionally glaucous.

1–3 mm diam., glabrous, occasionally glaucous.


lanceolate, pinnate, 10–45 × 4–15 cm, glabrous, gradually reduced distally;

proximal pinnae 3(–4)-pinnate;

rachis straight to flexuous, glabrous, not glaucous.

trowel-shaped, pinnate, 12–60 × 12–60 cm, gradually reduced distally, glabrous;

proximal pinnae 3-pinnate;

rachis straight, glabrous, not glaucous.

Ultimate segments

various, generally cuneate or fan-shaped to irregularly rhombic (plants in American southwest occasionally with segments nearly round), about as long as broad;

base broadly to narrowly cuneate;

margins shallowly to deeply lobed, incisions 0.5–7 mm, occasionally ± laciniate, sharply denticulate in sterile segments;

apex rounded to acute.

fan-shaped or rhombic, about as long as broad;

base cuneate;

apex rounded or acute, lobed, lobes separated by narrow incisions 0.5 mm wide.


transversely oblong or crescent-shaped, 1–3(–7) mm, glabrous.

transversely oblong to crescent-shaped, 0.5–2 mm, glabrous.


mostly 40–50 µm diam. 2n = 120.

mostly 40–58 µm diam. 2n = 60.


stalks 0.5–3.5 mm, dark color extending into segment base.

stalks 1–5 mm, with dark color ending abruptly at segment base, terminating in cupulelike swelling at base of segment (unlike any other species of Adiantum in the flora).

Adiantum capillus-veneris

Adiantum tenerum

Phenology Sporulating spring–summer. Sporulating throughout the year.
Habitat Moist calcareous cliffs, banks, and ledges along streams and rivers, walls of lime sinks, canyon walls (in the American southwest), around foundations, on mortar of storm drains Restricted to moist, shaded, limestone ledges, sink walls, and grottoes in the flora
Elevation 0–2500 m (0–8200 ft) 0–50 m (0–200 ft)
from FNA
AL; AR; AZ; CA; CO; FL; GA; KY; LA; MO; MS; NC; NM; NV; OK; SC; SD; TN; TX; UT; VA; BC; Mexico; Central America; West Indies; South America in Venezuela; Peru; tropical to warm temperate regions in Eurasia and Africa
[WildflowerSearch map]
[BONAP county map]
from FNA
FL; e,s Mexico; Central America in Guatemala; Honduras; Nicaragua; Costa Rica; South America in Venezuela
[BONAP county map]

No evident pattern to morphologic variation in the species is discernible, although a number of segregate species and infraspecific taxa have been recognized within North American Adiantum capillus-veneris. In the Eastern Hemisphere, the species is diploid, with 2n = 60 (I. Manton 1950). Several tetraploid counts have been reported from North America (W. H. Wagner Jr. 1963). Spore-measurement data suggest, however, that the polyploid cytotype may not be widely distributed. Further investigation is needed to determine whether Adiantum capillus-veneris populations in North America are conspecific with those in Eurasia and Africa.

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

Adiantum tenerum is readily distinguished from other species in the flora by the ultimate segments conspicuously articulate to the stalks.

(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. hispidulum, A. jordanii, A. melanoleucum, A. pedatum, A. tenerum, A. tricholepis, A. viridimontanum
A. aleuticum, A. capillus-veneris, A. hispidulum, A. jordanii, A. melanoleucum, A. pedatum, A. tricholepis, A. viridimontanum
Synonyms A. capillus-veneris var. modestum, A. capillus-veneris var. protrusum, A. capillus-veneris var. rimicola
Name authority Linnaeus: Sp. Pl. 2: 1096. (1753) Swartz: Prodr. 135. (1788)
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