Flora of North America species comparison

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Adiantum capillus-veneris

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

short-creeping;

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

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

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

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

proximal pinnae 3(–4)-pinnate;

rachis straight to flexuous, 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.
Indusia

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

mostly 40–50 µm diam. 2n = 120.
Segment

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

Adiantum capillus-veneris
Phenology Sporulating spring–summer.
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
Elevation 0–2500 m [0–8200 ft]
Distribution
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]
Discussion

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.)
Source FNA vol. 2. Treatment author: Cathy A. Paris.
Parent taxa Pteridaceae > Adiantum
Sibling taxa
A. aleuticum, A. hispidulum, A. jordanii, 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)
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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