Like other rare ferns of the Adirondacks, this species was not discovered until the early 20th century, with the earliest record in 1917 from Avalanche Lake. Woodsia alpina along with Woodsia glabella are two of the smallest ferns in our flora. The genus Woodsia is named after Joseph Woods, a 19th century English architect, botanist and geologist (Joseph Woods in Wikipedia, web site accessed 21 November 2007).
There are five existing populations but all of them consist of five or fewer plants, making them extremely vulnerable although they have persisted for many decades. There are four additional historical records which are not very exact, so locating such small plants will be difficult.
The existing populations are very small but most have persisted for many decades at this low-level. A couple of recent surveys have failed to relocate two populations but they still cannot be considered extirpated without further attempts. More survey work is needed to understand current trends in light of climate change.
This plant was always very rare in New York but the known populations have persisted for many decades. A few historical records still remain to be relocated but the difficulty of surveying such small populations prevent a precise knowledge of trends.
A severe drought or a rock fall could threaten plants since populations are very small and would be unable to recover. Unauthorized rock climbing could damage plants.
Make sure rock climbers do not affect populations. Establish sufficient buffers around populations to preserve the undisturbed aspect and hydrology of their habitat.
Determine if rock climbing is or could affect existing populations and whether it could also be used to search for new populations. Habitat preference studies could determine why this species is so rare in an area where its habitat seems common.
Its common name describes Woodsia alpina's habitat preferences in New York well. It is found in dry to moist, shaded, acidic cliffs or ledges in the mountains (New York Natural Heritage Program 2007). Rock crevices in cool sites (Gleason and Cronquist 1991). Shaded or exposed, damp to dry slaty or calcareous rocky banks (Fernald 1970).
In New York this fern is found chiefly in the Adirondacks, with a single site known in the Catskills.
Woodsia alpina has a circumboreal distribution. In North America it ranges from Alaska across most of Canada, and south to Maine, Vermont, New York, Michigan, and Minnesota.
Woodsia alpina is a small fern growing out of rock crevices. The leaves are 6-15 cm long and are sparsely hairy, with brown, lance-shaped scales 4-6 mm long near the base of the petiole. The petioles are jointed, so that the leaf stalks persist after the blades are gone. The blades are linear, only 1-2 cm wide.
The leaves emerge in late May, and the indusia (bearing the spores) form in July and persist until the leaves die in September.
Woodsia glabella and W. ilvensis are the other species of Woodsia in New York which have jointed petioles (and therefore, persistent leaf bases). W. glabella lacks hairs or scales above the leaf bases, and W. ilvensis has more pairs of pinnae segments (4-7) than does Woodsia alpina (2-3).
The leaves emerge in late May, and the indusia (spore-bearing structures) form in July, persisting until the leaves die in September.
The time of year you would expect to find Alpine Cliff Fern vegetative and fruiting in New York.
Alpine Cliff Fern
Woodsia alpina (Bolton) S.F. Gray
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New York Natural Heritage Program. 2021. New York Natural Heritage Program Databases. Albany, NY.
Weldy, T. and D. Werier. 2010. New York flora atlas. [S.M. Landry, K.N. Campbell, and L.D. Mabe (original application development), Florida Center for Community Design and Research http://www.fccdr.usf.edu/. University of South Florida http://www.usf.edu/]. New York Flora Association http://newyork.plantatlas.usf.edu/, Albany, New York
Weldy, Troy W. and David Werier. 2005. New York Flora Atlas. [S.M. Landry, K.N. Campbell, and L.D. Mabe (original application development), Florida Center for Community Design and Research. University of South Florida]. New York Flora Association, Albany, NY. Available on the web at (http://newyork.plantatlas.usf.edu/).
Information for this guide was last updated on: August 9, 2011
Please cite this page as:
New York Natural Heritage Program. 2021. Online Conservation Guide for Woodsia alpina. Available from: https://guides.nynhp.org/alpine-cliff-fern/. Accessed February 24, 2021.