New York Natural Heritage Program
Lowland Fragile Fern
Cystopteris protrusa (Weatherby) Blasdell
Ferns
Cystopteris protrusa fronds Stephen M. Young
Family: Wood-fern Family (Dryopteridaceae)

State Protection: Endangered
listed species are those with: 1) 5 or fewer extant sites, or 2) fewer than 1,000 individuals, or 3) restricted to fewer than 4 U.S.G.S. 7 minute topographical maps, or 4) species listed as endangered by U.S. Department of Interior.

Federal Protection: Not Listed

State Rarity Rank: S1
A State Rarity Rank of S1 means: This plant is endangered/critically imperiled in New York because of extreme rarity (typically 5 or fewer populations or very few remaining individuals) or is extremely vulnerable to extirpation from New York due to biological factors.

Global Rarity Rank: G5
A Global Rarity Rank of G5 means: This species is demonstrably secure globally, though it may be quite rare in parts of its range, especially at the periphery.


Did you know?
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.

State Ranking Justification [-]
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.

Short-term Trends [-]

Long-term Trends [-]