Thelypteris verecunda

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Thelypteris verecunda

No Common Name

ListedJuly 2, 1993
FamilyThelypteridaceae (Marsh fern)
DescriptionA ground fern.
HabitatMoist, shaded limestone ledges in tropical forest.
ThreatsHabitat loss by development or hurricanes, and collecting for horticultural use.
RangePuerto Rico


Thelypteris verecunda is a terrestrial fern with creeping rhizomes, about 0.07-0.11 in (2-3 mm) thick. The apex of the rhizome bears brown scales, about 0.04 in (1 mm) long. The fronds are of two types (dimorphic), one of which produces spores, while the other functions only in photosynthesis. The fronds have numerous star-shaped (or stellate) hairs, and many much longer, simple hairs. The stipes (or stalks of the fronds) are 0.4-0.6 in (1.0-1.5 cm) long and 0.02 in (0.4-0.5 mm) thick. The sterile blades are 1.0-1.6 in (2.5-4.0 cm) long and 0.6-0.8 in (1.5-2.0 cm) wide, and rounded at the broadly lobed tip. The fertile (spore-bearing) fronds are 5-6 in (13-15 cm) long and 0.5-0.7 in (1.2-1.8 cm) wide, with 15 to 20 pairs of rounded-oblong to oval, non-dissected pinnae (or lobes). The spore-bearing structures (or sori) are small and erect, have a minute indusium (a covering tissue), and bear a tuft of long, white, simple hairs.


T. verecunda is found at moist shaded limestone ledges at elevations of about 690 ft (200 m). The broader ecosystem type is montane tropical rainforest.


T. verecunda is a locally evolved (or endemic) species that is only known from three localities in Puerto Rico: Barrio Charcus in the municipality of Quebradillas, Barrio Bayaney in Hatillo, and Barrio Cidral in the municipality of San Sebastian.


The total known population of T. verecunda consists of only about 22 plants. The habitat in Barrio Bayaney consists on only about 20 plants, while those in Quebradillas and San Sebastian have only one known individual. All of the habitat of the rare fern is privately owned, and is therefore threatened by clearing and other disturbances. Because of its extreme rarity, this fern might also be an attractive item for illegal collecting for sale in the horticultural trade. Because of its tiny population and restricted range, the fern is also extremely vulnerable to the devastation of its habitat by a hurricane.

Conservation and Recovery

The critical habitat of T. verecunda is entirely located on private land. This habitat should be protected by acquisition and the establishment of ecological reserves, or by the negotiation of conservation easements. The rare fern must also be strictly protected from any collection of specimens. In addition, research should be conducted on its biology and habitat requirements, to provide knowledge for its management.


U. S. Fish and Wildlife Service
Regional Office, Division of Endangered Species
1875 Century Blvd., Suite 200
Atlanta, Georgia 30345

U. S. Fish and Wildlife Service
Boquerón Ecological Services Field Office
P.O. Box 491
Boquerón, Puerto Rico 00622-0491
Telephone: (787) 851-7297
Fax: (787) 851-7440


U. S. Fish and Wildlife Service. 2 July 1993. "Endangered and Threatened Wildlife and Plants: Determination of Endangered Status for Three Endemic Puerto Rican Ferns." Federal Register 58(126):35887-35891.

U. S. Fish and Wildlife Service. June 1994. "U. S. Fish and Wildlife Service, Division of Endangered Species, Species Account: Three Endemic Puerto Rican Ferns." U. S. Fish and Wildlife Service, Endangered Species Program. ( Date Accessed: July 6, 2000.