Thelypteris noveboracensis

Thelypteris noveboracensis
Scientific classification
Kingdom:	Plantae
Division:	Polypodiophyta
Class:	Polypodiopsida
Order:	Blechnales
Family:	Thelypteridaceae
Genus:	Thelypteris
Species:	T. noveboracensis
Binomial name
Thelypteris noveboracensis (L.) Nieuwl.
Synonyms
Dryopteris noveboracensis (L.) A. Gray Polypodium noveboracense L. Thelypteris thelypterioides (Michx.) Holub

Thelypteris noveboracensis, or the New York fern, is a fern found throughout the eastern United States and Canada. It is distinctive by its pinnae tapering to the base of the frond, and by its forming extensive clonal colonies on ridgetops and mountain benches. The only other native species in this area with similarly tapering pinnae is the ostrich fern, Matteuccia struthiopteris, which generally grows in riparian habitats. The only other species that forms as extensive clonal colonies is the hay-scented fern, Dennstaedtia punctilobula.

This fern grows in clumps of three or more fronds along a dark brown, slightly scaly rhizome, unlike the very similar Dennstaedtia punctilobula, which grows in lines. The blade is 8-25" long, yellow-green, and tapers at either end. It produces both fertile and sterile fronds. The fertile fronds are larger and more upright, and produce a few small, round sori near the margins of the pinnae. These sori are covered by a tan, kidney-shaped indusium.

Ecology

Thelypteris noveboracensis is common in sunny patches caused by canopy gaps in mixed woodlands, near vernal seeps, at the edge of swamps, and along streams. Once soil pH levels decline below 4.1, this fern can become a dominant understory species. In such situations, it may outcompete the seedlings of certain tree species, some of which are commercially important. The seedlings of Prunus serotina are especially vulnerable, as the fern releases an allelopathic phenol which can kill them.

This fern is a wetland indicator, and an endangered species in Illinois.

References

• USDA Plants Database: Thelypteris noveboracensis
• FEIS Database: Thelypteris noveboracensis
• Boughton C. 2005. Ferns of Northeastern and Central North America. New York: Houghton Mifflin. 417p.
• Rhoads AF, Block TA. 2007. The Plants of Pennsylvania. Philadelphia: University of Pennsylvania Press. 1042 p.