BC Conservation Data Centre: Species Summary
Adiantum capillus-veneris
southern maiden-hair fern
| Scientific Name: | Adiantum capillus-veneris L. | ||||||||||
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| English Name: | southern maiden-hair fern | ||||||||||
| Classification / Taxonomy | |||||||||||
| Scientific Name - Concept Reference: | Kartesz, J.T. 1994. A synonymized checklist of the vascular flora of the United States, Canada, and Greenland. 2nd edition. 2 vols. Timber Press, Portland, OR. | ||||||||||
| Classification Level: | Species | ||||||||||
| Species Group: | Vascular Plant | ||||||||||
| Species Code: | ADIACAP | ||||||||||
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| Conservation Status / Legal Designation | |||||||||||
| Global Status: | G5 (Aug 2016) | ||||||||||
| Provincial Status: | S1 (Apr 2019) | ||||||||||
| BC List: | Red | ||||||||||
| Provincial FRPA list: | |||||||||||
| Provincial Wildlife Act: | |||||||||||
| COSEWIC Status: | Endangered (May 2011) | ||||||||||
| SARA Schedule: | 1 - Endangered (Jun 2003) | ||||||||||
| General Status Canada: | 1 - At Risk (2010) | ||||||||||
| Ecology & Life History | |||||||||||
| General Description: | Adiantum capillus-veneris is a fern with creeping rhizomes (i.e., spreading laterally) and fragile-looking, twice- or thrice-pinnately compound leaves with leaf blades from 8-30 cm in length (Lellinger 1985). The slender, dark rachis (stem) is smooth and shiny. | ||||||||||
| Technical Description: | From CNHP Wetland Guide 2012: Plants terrestrial. Stems short-creeping; scales golden brown to medium brown, 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. Segment stalks 0.5--3.5 mm, dark color extending into segment base. 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. From CNHP Wetland Guide 2012: Plants terrestrial. Stems short-creeping; scales golden brown to medium brown, 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. Segment stalks 0.5--3.5 mm, dark color extending into segment base. 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. |
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| Diagnostic Characteristics: | This is the only Adiantum found at lower elevations. It is distinctive in its broad, delicate, fan-shaped leaflets. The sori (clusters of spore bearing structures) are marginal, borne beneath reflexed margins of the lobes on the leaf segments. From CNHP Wetland Guide 2012: Main Characteristics: Ultimate leaf segments fan-shaped or irregularly rhombic Frond once pinnate with a single main axis Sori discontinuous and borne on the reflexed margins of the upper lobes of ultimate segments |
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| Subspecies Comments: | No subspecies of Adiantum capillus-veneris are recognized in B.C. | ||||||||||
| Identification Comments: | Adiantum capillus-veneris is a delicate drooping fern arising from a thin, black-tinged rhizome. Fronds are frequently bipinnate with each frond consisting of 5-12 alternate pinnae. Each pinna is comprised of approx. 6 pinnules which are widely separated and arranged on each side of a central axis. Pinnules are oval to fan-shaped, broadly rounded at the tips with rounded teeth and tapered at the base (reminiscent of Gingko leaves). Sori on fertile leaves are clustered on the lower pinnule surface within crescent-shaped false indusia formed by inrolled leaf margins (Douglas et al. 2000; White and Douglas 1998). | ||||||||||
| Similar Species: | Adiantum capillus-veneris can be distinguished from Adiantum aleuticum, the only other Adiantum species in B.C., by its lax drooping habit, unbranched stem, arrangement of pinnae on both sides of the stem, and pinnules that are oval to fan-shaped (Brunton 1984). A. aleuticum is a taller, upright fern, which has a palmately-branched (equally two-forked) stem with oblong, almost rectangular (2-4 times longer than wide) pinnules. The two Adiantum species are not likely to be confused because they occupy different habitats: A. aleuticum occupies shaded acidic woods and rocky slopes while A. capillus-veneris is a calciphile, growing in seepy sites on calcareous rocks, including tufa (Brunton 1984). | ||||||||||
| Provincial Reproduction Comments: | Adiantum capillus-veneris reproduces vegetatively through rhizome growth and can expand rapidly into large colonies (Brunton 1984). In South Dakota (the nearest known locality), it appears to also spread vegetatively when clumps or plants are dislodged and transported downstream and become lodged elsewhere along the stream bank or edge of pools, thereby creating new colonies (Hornbeck et al. 2003). It is likely that this mode of dispersal occurs at Fairmont Hot Springs. It is not known if new colonies are being formed from spore dispersal events. (Spores are wind-dispersed in Adiantum). It is not known whether sexual reproduction is occurring. No gametophytes have been located at the sites (Smith 2004). The humid microclimate and proximity to water would be conducive to spore germination, gametophyte development, and fertilization of gametes. The gametophyte is bisexual in A. capillus-veneris, and it is not known whether it is predominantly out-crossing or self-fertile. The predominance of vegetative spread or self-fertilization of gametes can result in low genetic variability within populations; therefore, it is important to determine the ratio of sexual vs. asexual reproduction for this species. | ||||||||||
| Provincial Ecology Comments: | Adiantum capillus-veneris requires very specific conditions to survive, particularly in B.C., the northern limit of its range. It is strictly dependent on tufa substrates (porous calcium carbonate rock formed by precipitation from lime-rich mineral springs) and proximity to hot springs water flow (Brunton 1984; White and Douglas 1998; Smith 2004). Adiantum capillus-veneris is a poor competitor; therefore, it is also restricted to early seral stages of tufa formation (Brunton 1984). Dramatic changes in population size have been observed; suitable habitats are rapidly colonized while adverse changes to habitat conditions can result in great reductions in population size (Smith 2004). Little is known about the basic ecology of A. capillus-veneris. For example, there is limited information about its pests, predators (low palatability of fern suggests few predators), diseases, competitors, optimal habitat conditions (water temperature, flow chemistry), and rates of recruitment, mortality, and growth. In fact, only the number of fronds is known from the site; the number of individual plants is unknown. The number of years to reach maturity (spore production) is also not known. | ||||||||||
| Habitats: (Type / Subtype / Dependence) |
Springs / Hot Spring / Obligate
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| Global Habitat Comments: | Adiantum capillus-veneris occurs on moist, rocky areas - including moist cliffs and seeps (especially on calcareous or alkaline rocks or in very mineralized soil) (Cronquist et al. 1972), springs, wet stream banks (Great Plains Flora Association 1986), within the spray of waterfalls (Lellinger 1985), canyon walls in the southwest U.S., on building foundations, and on the mortar of storm drains. It is found at elevations from 0-2500 meters (Flora of North America Editorial Committee 1993). It generally inhabits moist cliffs or slopes (Gleason and Cronquist 1963). | ||||||||||
| Provincial Habitat Comments: | Adiantum capillus-veneris is found on wet or seepy calcareous rock walls adjacent to lime-rich hot springs (Smith 2004). Specifically, it requires a tufa substrate (very porous calcium carbonate rock). The year-round warm temperatures and humid microclimate facilitated by the hot springs habitat at the location in B.C. allow this species to survive in a cooler, more northerly region (1000 km north) than its main range (Brunton 1984). A. capillus-veneris also requires bare or sparsely vegetated rock faces that are formed by continual tufa deposition. On older deposits that support an abundance of herbs and shrubs, the species is unable to compete and dies back. Associated species at the B.C. sites include Juniperus horizontalis, Epipactis gigantea, Dichanthelium acuminatum var. fasciculatum, Carex scirpoidea, Muhlenbergia glomerata, Agropyron repens, and Arctostaphylos uva-ursi (Smith 2004). The population occurs in the Interior Douglas-fir zone, IDFdm2 (Douglas et al. 2002). | ||||||||||
| Provincial Phenology: (1st half of month/ 2nd half of month) |
Jan: Vegetative / Vegetative
Feb: Vegetative / Vegetative Mar: Vegetative / Vegetative Apr: Vegetative / Vegetative May: Vegetative / Vegetative Jun: Vegetative / Vegetative Jul: Vegetative, Fruiting / Vegetative, Fruiting Aug: Vegetative, Fruiting / Vegetative, Fruiting Sep: Vegetative, Fruiting / Vegetative, Fruiting Oct: Vegetative / Vegetative Nov: Vegetative / Vegetative Dec: Vegetative / Vegetative |
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| Provincial Phenology Comments: | Phenology for Adiantum capillus-veneris is not accurately known. It is an evergreen species and is known to produce mature spores in late summer in South Dakota, the nearest known location (Hornbeck et al. 2003). Spore production was noted at all subpopulations in 2002 and 2003 in late July - early August in B.C. (Smith 2004). It is not known when or if spores germinate at the sites nor when gametophytes develop. | ||||||||||
| Elevation (m) (min / max): | Provincial: 1000 / 1000 | ||||||||||
| Known Pests: | |||||||||||
| Pollen Vector: | |||||||||||
| Pollinator: | |||||||||||
| Dispersal: | |||||||||||
| Provincial Inventory | |||||||||||
| Inventory Priority: | D - Low | ||||||||||
| Ownership of occurrences (Known locations): | Mostly private | ||||||||||
| Inventory Need: | Adiantum capillus-veneris is restricted to a very small area at Fairmont Hot Springs Resort. It is unlikely that further inventories at other B.C. hot springs will yield new populations; however, the entire hot springs system at Fairmont Hot Springs should be surveyed periodically to ensure that all extant populations/subpopulations have been located. | ||||||||||
| Inventory Comments: | Other hot springs in southeastern B.C. were intensively sampled in 1949, and an undeveloped hot springs with suitable habitat was surveyed in 1983 for Adiantum capillus-veneris, but no additional plants were found in either search (Smith 2004; Brunton 1984). It is unclear from previous reports (White and Douglas 1998; Smith 2004) how much of the Fairmont Hot Springs Resort was intensively surveyed prior to 2000-2003. If it is assumed that the entire area was surveyed repeatedly in the past, then the recent discovery of three new subpopulations between 2000 and 2003 suggests that the colonization of new localities is a dynamic process. A. capillus-veneris can rapidly colonize newly formed tufa habitats, creating new vigorous populations in areas not previously occupied. Likewise, known populations can be extirpated just as dramatically if changes occur in hot springs water flow and tufa substrates. | ||||||||||
| Economic Attributes | |||||||||||
| Global Economic Use: |
FOOD
MEDICINE/DRUG OTHER USES/PRODUCTS |
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| Provincial Economic Use: |
Cultivated ornamental
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| Global Economic Comments: | This species appears to have had some minor Native American medicinal use (Weiner 1980). It is used for coughs and is sometimes combined with licorice or licorice fern (Polypodium spp.) for this purpose. In decoction or as a syrup it makes a soothing, cooling drink for flu, fevers, and inflammation. It also is used to promote healthy hair (AllHerb 2000). It is reported to be used in the southwestern U.S. for building bones and cartilage; and it has similar uses as horsetails and nettles (Robyn Klein, pers. comm.). Prices for this species were found as follows: U.S., Internet: $24.71/120 tablets. |
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| Provincial Economic Comments: | In B.C., Adiantum capillus-veneris is cultivated as an ornamental for outdoor landscaping. It is also commonly cultivated elsewhere, particularly in greenhouses (Hoshizaki 1970 in Hornbeck et al. 2003). A. aleuticum, the only other Adiantum species in B.C., is also cultivated as an ornamental in outdoor gardens in B.C. A. capillus-veneris was reportedly used medicinally by First Nations groups in the United States. It was used as an anti-rheumatic by the Mahuna people of California, and as a treatment for insect stings and a psychological treatment for insanity by Kayenta Navajo people of Arizona (Moerman 1998 in Hornbeck et al. 2003). | ||||||||||
| Distribution | |||||||||||
| Endemic: | N | ||||||||||
| Global Range Comment: | This species is globally widespread in tropical and warm-temperate regions, including Eurasia, Africa, the West Indies, Central America and South America (in Venezuela and Peru). The North American range includes roughly the southern one-third of the U.S., with additional disjunct populations in South Dakota and British Columbia (Flora of North America Editorial Committee 1993). In North America, it is sometimes escaped from cultivation north of its natural range (Lellinger 1985, Gleason and Cronquist 1963). Populations in California may be introduced (Hickman 1993). Known in Colorado (Moffat, Mesa, Montrose, Ouray, Montezuma and Las Animas counties). |
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| Disjunct, more common elsewhere: | Y | ||||||||||
| Peripheral, major distribution elsewhere: | Y | ||||||||||
| Authors / Contributors | |||||||||||
| Global Information Author: | S. SPACKMAN, D. ANDERSON & S. THOMAS; REV. E. NIELSEN; rev. Parker, J. (2010). | ||||||||||
| Last Updated: | May 12, 2010 | ||||||||||
| Provincial Information Author: | Bartemucci, P. | ||||||||||
| Last Updated: | Feb 08, 2005 | ||||||||||
| Last Literature Search: | |||||||||||
| References and Related Literature | |||||||||||
B.C. Ministry of Environment. Recovery Planning in BC. B.C. Minist. Environ. Victoria, BC. |
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Brunton, D.F. 1984. Status Report on Southern Maiden-hair Fern, Adiantum capillus-veneris, in Canada. Unpubl. rep. submitted to the Comm. on the Status of Endangered Wildl. in Can. Ottawa. 33pp. |
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Carr, Bill. Botanist, Texas Conservation Data Center. |
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Cronquist, A., A.H. Holmgren, N.H. Holmgren, and J.L. Reveal. 1972. Intermountain flora: vascular plants of the intermountain West, U.S.A. Volume One. Hafner Publishing Company, New York. 270 pp. |
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Douglas, G.W., D. Meidinger, and J. Penny. 2002. Rare Native Vascular Plants of British Columbia, 2nd ed. B.C. Conserv. Data Centre, Terrestrial Inf. Branch, Victoria. 358pp. |
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Douglas, G.W., D. Meidinger, and J. Pojar, eds. 2000. Illustrated Flora of British Columbia, Vol. 5, Dicotyledons (Salicaceae through Zygophyllaceae) and Pteridophytes. B.C. Minist. Environ., Lands and Parks, and B.C. Minist. For., Victoria. 389pp. |
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Drozda, Nick. Field Botanist, Kentucky State Nature Preserves Commission, Frankfort, KY |
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Flora of North America Editorial Committee (FNA). 1993a. Flora of North America north of Mexico. Vol. 2. Pteridophytes and gymnosperms. Oxford Univ. Press, New York. xvi + 475 pp. |
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Gleason, H.A., and A. Cronquist. 1963. Manual of vascular plants of northeastern United States and adjacent Canada. D. Van Nostrand Company, New York, NY. 810 pp. |
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Great Plains Flora Association. 1986. Flora of the Great Plains. University of Kansas Press, Lawrence. 1392 pp. |
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Hickman, J. C., ed. 1993. The Jepson manual: Higher plants of California. University of California Press, Berkeley, CA. 1400 pp. |
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Hitchcock, C.L., and A. Cronquist. 1973. Flora of the Pacific Northwest: An Illustrated Manual. University of Washington Press, Seattle, Washington. 730 pp. |
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Hornbeck, J.H., D. Ryder, C. Hull Seig and R.W. Cook. 2003. Conservation assessment for southern maidenhair fern and stream orchid in the Black Hills National Forest South Dakota and Wyoming. Unpublished report. USDA Forest Service, Rocky Mountain Region, Black Hills National Forest. Custer, South Dakota, USA. 45 pages. |
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Hoshizaki, B. 1970. The genus Adiantum in cultivation. Baileya 17: 145-190. |
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Kartesz, J.T. 1999. A synonymized checklist and atlas with biological attributes for the vascular flora of the United States, Canada, and Greenland. First edition. In: Kartesz, J.T., and C.A. Meacham. Synthesis of the North American Flora, Version 1.0. North Carolina Botanical Garden, Chapel Hill, N.C. |
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Klein, Robyn. Instructor, Sweetgrass School of Herbalism. Personal communication. |
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Lellinger, D.B. 1985. A field manual of the ferns and fern-allies of the U.S. and Canada. Smithsonian Institution Press, Washington, DC. 389 pp. |
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McGuffin, Michael. Personal communication. American Herbal Products Association, Silver Spring MD |
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Ode, David. Botanist/Ecologist, South Dakota Natural Heritage Database. Personal communication. |
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Smith, S. 2003. National Recovery Plan for Southern Maidenhair Fern (Adiantum capillus-veneris). Unpublished. 25 pages. |
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Smith, Tim. Personal communication. Botanist, Missouri Department of Conservation. Missouri Department of Conservation, Jefferson City, MO |
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Southern Maiden-hair Fern Recovery Team. 2007. Recovery strategy for the southern maiden-hair fern (Adiantum capillus-veneris) in British Columbia. Prepared for the B.C. Ministry of Environment, Victoria, BC. 17pp. |
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Weiner, M.A. 1980. Earth Medicine Earth Food. Ballantine Books, New York. 230 pp. |
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White, D.J., and G.W. Douglas. 1998. Update COSEWIC Status Report on Southern Maiden-hair Fern, Adiantum capillus-veneris, in Canada. Unpubl. Rep. submitted to the Comm. on the Status of Endangered Wildl. in Can. Ottawa. 13pp. |
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Please visit the website Conservation Status Ranks for definitions of the data fields used in this summary report.
Suggested Citation:
B.C. Conservation Data Centre. 2010. Species Summary: Adiantum capillus-veneris. B.C. Minist. of Environment. Available: https://a100.gov.bc.ca/pub/eswp/ (accessed Jun 19, 2026).