CPC National Collection Plant Profile

Adiantum viridimontanum

William Cullina

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CPC National Collection Plant Profile

Adiantum viridimontanum

Common Name: 
Green Mountain maidenhair fern
Growth Habit: 
CPC Number: 


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Adiantum viridimontanumenlarge
Photographer: William Cullina

Adiantum viridimontanum is Fully Sponsored
Primary custodian for this plant in the CPC National Collection of Endangered Plants is: 
Elizabeth J. Farnsworth contributed to this Plant Profile.

Adiantum viridimontanum

Adiantum viridimontanum is a slender fern that grows up to 75 cm (2.5 feet) tall. This species can be found in Vermont and Quebec in habitats that have exposed rock, some of which is mined for asbestos. These rocky areas (called serpentine habitat) typically support only sparse vegetation comprised of the few species (some rare) that can tolerate the very mineral-rich but shallow soil found here. Recent botanical inventories have turned up 7 populations in Vermont and 14 in Quebec. In Vermont, most populations appear stable and are restricted to relatively isolated sites, one of which is protected. However, this species faces a number of threats to its long-term survival, including mining of the rocky habitat where it occurs, road widening activities in areas where the plant occurs in road cuts, and the negative impacts of invasive species.

Research and Management Summary:
A handful of individuals/organizations are conducting research on this species. Conservation organizations on both sides of the border are beginning to take steps to protect these unique serpentine areas, which harbor many rare and specialized plant species.

Plant Description:
The leaves of this fern are slender, 30 - 75 cm (1 - 2.5 ft) long, with shiny, water-resistant surfaces and dark, glabrous petioles (Ruesink 2001). In high light, the leaves are held upright, while in shadier conditions, they spread horizontally, resembling horseshoes. The more triangular, fertile frond extends beyond the leaves and bears sori (reproductive structures) on dark brown, false indusia on its margins during late summer and fall.

Distribution & Occurrence

State Range
State Range of  Adiantum viridimontanum
  Adiantum viridimontanum has been described from a variety of habitats where serpentine rock (composed of dunnite or serpentinite) is exposed, including asbestos quarries, road cuts, talus slopes, and cliffs. These outcrops typically support only sparse vegetation comprised of the few species (some rare) that can tolerate the excessively mineral-rich chemistry of the shallow soil that weathers from cracks in the rock (Thomspon and Sorenson 2000).

Like other plant species that occur in these habitats, Adiantum viridimontanum appears to thrive best in direct sunlight, where cover of other plant species is low. In this sense, the fern behaves like a typical disturbance colonizer and may even require disturbances to recruit and establish at new sites (Ruesink 2001).

According to Ruesink (2001), grasses and herbaceous species associated with the fern in Vermont include: harebell (Campanula rotundifolia), field chickweed (Cerastium arvense), hairgrass (Deschampsia flexuosa), rock sandwort (Arenaria stricta), and poverty grass (Danthonia spicata). Common juniper (Juniperus communis var. depressa) dominates the shrub layer, while red spruce (Picea rubra) and gray birch (Betula populifolia) make up a canopy of usually stunted trees.

  Adiantum viridimontanum is endemic to Vermont (USA) and southern Quebec (Canada).

Number Left
  21 occurrences of Adiantum viridimontanum are recorded from Vermont and Quebec. Vermont occurrences are estimated to contain a total of approximately 2000 plants.


Global Rank:  
Guide to Global Ranks
Federal Status:  
Guide to Federal Status
Recovery Plan:  

State/Area Protection
  State/Area Rank Status Date  
  Canadian National Rank N2 5/18/1999  
  Quebec S2  
  U. S. National Rank N2 7/25/1996  
  Vermont S2 T 3/1/2000  

Conservation, Ecology & Research

Ecological Relationships
  Adiantum viridimontanum reproduces most commonly via vegetative propagation (Ruesink 2001).

Because populations are widely isolated from each other, gene flow is likely to be small, and genetic diversity of populations may be low. Spore dispersal is thought to be quite local, within a few meters of the parent plant (Ruesink 2001).

Herbivory has not been observed on the fern. This is most likely attributed to the fact that fern leaves often contain high levels of secondary compounds, including tannins and phenolics, which (Ruesink 2001).

  Mining -- While most mining of serpentine for asbestos has ceased in the United States, this activity continues in Quebec and can threaten ferns directly. The use of former quarries in Vermont is of some concern, as well; one was formerly proposed to be a dump site for asbestos and other solid waste (Ruesink 2001).

Road construction -- Where the fern occurs on steep road cuts, it is threatened by road-widening and other maintenance activities.

Invasive species -- Certain invasive plant species (including Microstegium vimineum, Rhamnus cathartica, Alliaria petiolata, and Lonicera spp.) have invaded other serpentine sites in the northeast, and must be watched for incursions on A. viridimontanum habitat, especially on gentler talus slopes and hillsides that support deeper soils.

Small habitat size -- Its apparently extreme specialization to an uncommon bedrock type means that this species, like other serpentine plants, will be confined to a small geographical area with sparse and far-flung populations that are vulnerable to local extinction.

Current Research Summary
  Ongoing genetic studies by Dr. Catherine Paris (University of Vermont, Burlington, Vermont) have established electrophoretic protocols for distinguishing Adiantum viridimontanum from its congeners that overlap with its distribution. Dr. Paris is also studying the distribution of the fern along environmental gradients, and how it interacts with other members of the Adiantum pedatum complex (see her web site, http://www.uvm.edu/~plantbio/faculty/paris.html, for more information).

Dr. Geoffrey Hall, Botanist with the Quebec office of The Nature Conservancy - Canada, is leading an effort to document and evaluate populations of Adiantum viridimontanum in Quebec in order to prioritize protection and management efforts (Hall 1998).

Spores have been collected from several Vermont populations for spore banking by the New England Plant Conservation Program (New England Wild Flower Society, Framingham, Massachusetts). Plants were successfully grown from some of these spores, but most plants died following transplantation. However, there is at least one nursery in New England that is successfully propagating the plant. Several plants and a small amount of seed (from one population) in cold storage are currently in the New England Wild Flower Society's rare plant collection.

Current Management Summary
  One site in Lowell, Vermont is protected by The Nature Conservancy (Vermont Chapter), which has been actively working with landowners there since 1983.

The Vermont Nongame and Natural Heritage Program, as well as volunteer task forces of the New England Plant Conservation program, have monitored several populations of the fern throughout Vermont for several years, but no assessment of population viability or trends has been performed to date.

Only one serpentine site in Quebec is currently protected (Tremblay 1994). According to Ruesink (2001), the Quebec Ministry of the Environment and The Nature Conservancy Canada recently purchased a large serpentine area with a large maidenhair fern population, at Mont Caribou, which will be designated an ecological reserve.

Research Management Needs
  Collaboration with transportation authorities and private mining interests to encourage activities compatible with conservation of this species and its required habitat

International cooperation between Canadian and U. S. conservation organizations to protect the fern

Regular monitoring for the presence of invasive species that can outcompete the fern

Standardized techniques for quantifying population size

Population viability analysis

Genetic studies to determine homozygosity levels and effects of inbreeding on populations and to assess interactions among members of the Adiantum pedatum complex

Studies of factors limiting sporophyte establishment, including light, moisture, soil chemistry, microclimate, and pathogens

Ex Situ Needs
  Studies are needed of improved techniques for long-term spore banking and fern propagation


Books (Single Authors)

Dann, K.T. 1988. Traces on the Appalachians: A natural history of serpentine in eastern North America. New Brunswick, New Jersey: Rutgers University Press.

Thompson, E.H.; Sorenson, E.R. 2000. Wetland, Woodland, Wildland: A guide to the natural communities of Vermont. Waterbury, Vermont: The Nature Conservancy and the Vermont Department of Fish and Wildlife.

Books (Sections)

Flora of North America Editorial Committee. 1993. Vascular Cryptogams through Gymnosperms. Flora of North America North of Mexico. p 2: i--xvi, 1--475.

Electronic Sources

(2001). New England Botanical Club map of the Vermont distribution of the fern. New England Botanical Club, Harvard University Herbaria, Cambridge, Massachusetts, USA. http://www.herbaria.harvard.edu/~rangelo/Neatlas0/NE0-35d.html. Accessed: 2002.

NatureServe. (2008). NatureServe Explorer: An online encyclopedia of life [web application]. [Internet].Version 7.0. NatureServe, Arlington, Virginia. http://www.natureserve.org/explorer. Accessed: (June 17, 2008).

Journal Articles

Fernald, M.L. 1905. An alpine Adiantum. Rhodora. 7, 190-192

Jolley, L.F. 1922. A variety of maidenhair fern new to Vermont. Joint Bulletin of the Vermont Botanical and Bird Clubs. 8: 40-41.

Kruckeberg, A.R. 1954. The ecology of serpentine soils. III. Plant species in relation to serpentine soils. Ecology. 35: 267-274.

Paris, C.A. 1991. Adiantum viridimontanum, a New Maidenhair Fern in Eastern North-America. Rhodora. 93, 874: 105-121.

Paris, C.A.; Windham, M.D. 1988. A biosystematic investigation of the Adiantum pedatum complex in eastern North America. Systematic Botany. 13, 240-255

Zika, P.F.; Dann, K.T. 1985. Rare plants on ultramafic soils in Vermont. Rhodora. 87: 293-304.


Hall, G. 1998. Proposition de caracteristiques standards pour l'identification et l'evaluation de la qualite des occurrences de 35 plantes menacees ou vulnerables au Quebec: Adiantum viridimontanum. Quebec City, Quebec: Prepared for the Quebec Conservation Data Centre.

Ruesink, A. 2001. Adiantum viridimontanum Paris (Green mountain maidenhair fern) Conservation and Research Plan. Framingham, Massachusetts: New England Wild Flower Society.

Tremblay, R.L. 1994. 'Et la reserve ecologique au Mont Gosford?'; L'Echo de Frontenac. Frontenac, Quebec, Canada:


O'Connor, K. 1995. Geography and ecology of Adiantum viridimontanum, a rare fern species in Vermont. [Undergraduate research thesis]: University of Vermont. Burlington, Vermont.

  This profile was updated on 3/4/2010
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