This is one of our plants that, while rare, was also once widespread across the state south of the Adirondacks. There is one occurrence known from eastern Long Island, one from Staten Island, one from Tompkins County, and two from near Lake Erie. The reason for this may be that, while it is common across southern Pennsylvania, it is mostly absent from the northern part of the state with a few populations extending the range of the species into New York.
There is one existing population and it contains thousands of plants. There are three populations from the early 1900s which have not been resurveyed but habitat still exists. A population from 1899 is now extirpated because its habitat no longer exists.
The single population on Staten Island continues to do well.
Only five populations of this fern have ever been known from the state. Of the five only one is currently known to exist.
The known population may be threatened by future development in the natural areas that surround it. This may produce more visitation to the site and introduce unwanted disturbance to the plants.
A natural buffer should be maintained around the population and a backup population should be maintained at a local botanical garden.
The only extant record in the state is from a sugar maple forest on a steep slope, growing on serpentine soil. (New York Natural Heritage Program 2010). In soil of moist, deciduous forest (FNA 1993). Mesic woods (Gleason & Cronquist 1991). Most rich (often calcareous) wooded slopes, rocky banks or alluvium (Fernald 1970).
This fern is currently known from Staten Island with historical records from the North Fork of Long Island in Suffolk County, Tompkins County in the Finger Lakes area, and Erie County in western New York.
This fern is most common from Pennsylvania across the northern Midwest to Iowa and south to Arkansas, Alabama, and western North Carolina and Virginia. It extends south to the panhandle of Florida and into a few areas of South Carolina while reaching its northern limits in New England, New York, and Ontario. The drier climate prevents its spread west from eastern Nebraska, Kansas, and Oklahoma.
Cystopteris protrusa is a fern species with creeping, perennial, yellow-hairy stems. It grows rooted in the soil (as opposed to clinging to rocks or cliffs). Early season leaves are sterile, coarsely divided, and have rounded teeth. Later (late spring and early summer) leaves are larger (up to 45 cm long), finely divided, have sharp-pointed teeth,and are fertile. The pinnae (leaflets) are held roughly perpendicular to the petiole, have toothed margins, and are not hairy or glandular (FNA 1993).
Lowland Fragile Fern can be identified any time the fronds are present.
Lowland fragile fern is our only Cystopteris species that grows on the forest floor rather than on rocks or cliffs, and whose stem has yellow hairs and protrudes past the current season's frond.
Cystopteris protrusa produces spores from mid-May to early August.
The time of year you would expect to find Lowland Fragile Fern vegetative and fruiting in New York.
Lowland Fragile Fern
Cystopteris protrusa (Weatherby) Blasdell
Fernald, M. L. 1950. Gray's manual of botany. 8th edition. Corrected printing (1970). D. Van Nostrand Company, New York. 1632 pp.
Flora of North America Editorial Committee. 1993. Flora of North America, North of Mexico. Volume 2. Pteridophytes and Gymnosperms. Oxford University Press, New York. 475 pp.
Gleason, Henry A. and A. Cronquist. 1991. Manual of Vascular Plants of Northeastern United States and Adjacent Canada. The New York Botanical Garden, Bronx, New York. 910 pp.
Holmgren, Noel. 1998. The Illustrated Companion to Gleason and Cronquist's Manual. Illustrations of the Vascular Plants of Northeastern United States and Adjacent Canada. The New York Botanical Garden, Bronx, New York.
Mitchell, Richard S. and Gordon C. Tucker. 1997. Revised Checklist of New York State Plants. Contributions to a Flora of New York State. Checklist IV. Bulletin No. 490. New York State Museum. Albany, NY. 400 pp.
New York Natural Heritage Program. 2010. Biotics database. New York Natural Heritage Program. New York State Department of Environmental Conservation. Albany, NY.
New York Natural Heritage Program. 2020. New York Natural Heritage Program Databases. Albany, NY.
Reschke, Carol. 1990. Ecological communities of New York State. New York Natural Heritage Program, New York State Department of Environmental Conservation. Latham, NY. 96 pp. plus xi.
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
This guide was authored by: Stephen M. Young
Information for this guide was last updated on: September 6, 2012
Please cite this page as:
New York Natural Heritage Program. 2020. Online Conservation Guide for Cystopteris protrusa. Available from: https://guides.nynhp.org/lowland-fragile-fern/. Accessed January 27, 2020.