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

adiantum, California maidenhair, California maidenhair fern



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


scales reddish brown, concolored, margins entire.


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

arching or pendent, clustered, 30–45 cm.


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

1–1.5 mm diam., glabrous, not glaucous.


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

proximal pinnae 3(–4)-pinnate;

rachis straight to flexuous, glabrous, not glaucous.

lanceolate, pinnate, 20–24 × 8–10 cm, gradually reduced distally, glabrous;

proximal pinnae 3(–4)-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, not quite as long as broad;

base truncate or broadly cuneate;

margins of fertile segments unlobed but very narrowly incised, sterile segments with margins lobed, denticulate;

apex rounded.


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

transversely oblong, 3–10 mm, glabrous.


mostly 40–50 µm diam. 2n = 120.

mostly 40–50 µm diam. 2n = 60.


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

stalks 1–4 mm, with dark color ending abruptly at segment base.

Adiantum capillus-veneris

Adiantum jordanii

Phenology Sporulating spring–summer. Sporulating early spring–midsummer.
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 Seasonally moist, shaded, rocky banks, canyons, and ravines
Elevation 0–2500 m (0–8200 ft) 0–1000 m (0–3300 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
CA; OR; Mexico in Baja California
[WildflowerSearch map]
[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 jordanii occasionally hybridizes with A. aleuticum where their ranges overlap in northern California, yielding the sterile hybrid Adiantum × tracyi C. C. Hall ex W. H. Wagner. Adiantum × tracyi, morphologically intermediate between its parental species, can be distinguished from A. jordanii by its broadly deltate leaf blade that tapers abruptly from the 4(–5)-pinnate base to a 1-pinnate apex. It is best separated from A. aleuticum by leaf blades with a strong rachis, and by ultimate blade segments that are less than twice as long as broad. Adiantum × tracyi shows 59 univalents at metaphase; its spores are irregular and misshapen (W. H. Wagner Jr. 1962).

(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. melanoleucum, A. pedatum, A. tenerum, 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) Müller Halle: Bot. Zeitung 1864: 26. (1864)
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