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*The following is based on Gann, G.D., K.A. Bradley & S.W. Woodmansee. 2002. Rare Plants of South Florida: Their History, Conservation, and Restoration. The Institute for Regional Conservation: Miami. For updated species accounts, see Citation below. For the original text, follow the link in the Update field. If no Update field is displayed, then cite as the original publication.

Cyperus floridanus Britton

Florida flatsedge

South Florida Status: Imperiled. For a list of conservation areas, see the main species page in the Floristic Inventory of South Florida.

Taxonomy: Monocotyledon; Cyperaceae.

Habit: Perennial terrestrial herb.

Distribution: Native to South Florida, the Bahamas, and Cuba.

South Florida Distribution: Collier and Miami-Dade counties and the Monroe County Keys.

South Florida Habitats: Rockland hammocks, shell mounds, and open sand.

Protection Status: Listed as endangered by FDACS and as critically imperiled by FNAI.

Aids to Identification: There are about 50 species of Cyperus in Florida. Wunderlin (1998) has a key. In Florida this is a very small plant, usually about five cm or less in height.

References: Small, 1933a; McLaughlin, 1944; Long & Lakela, 1976; Correll & Correll, 1982; Wunderlin, 1998; Coile, 2000.

Synonyms: C. filiformis Sw., misapplied; C. filiformis var. densiceps Kük.

Historical Context: John Loomis Blodgett first collected Florida flatsedge between 1838 and 1853 on the island of Key West (s.n., NY, US). Abram P. Garber also collected it on Key West in 1877 (1221, NY, FLAS). In 1903, Nathaniel L. Britton described Blodgett’s plant as a new species, designating his Key West collection the type (in Small, 1903). It was not seen in the Florida Keys again until George N. Avery discovered it persisting at the Key West Cemetery in 1965 (Avery’s Notes, 13 March 1965). Avery vouchered this population in 1978 (1898, FLAS, FTG). Bradley re-vouchered this population in 1995 (268, FTG), and observed plants in and around the cemetery in 2001.

The next station was discovered by Garber, who collected it in Miami in 1877 (1220, NY). Florida flatsedge was not seen in Miami-Dade County again until John Popenoe and others collected it on Key Biscayne at Bill Baggs Cape Florida State Park in 1983 (2345, FTG, USF). Bradley re-vouchered it at this station in 1995 (242, FTG). Gann has observed plants, nearly throughout the park, as recently as 2000. In 1995, Gann and Bradley discovered a station on the mainland at the R. Hardy Matheson Preserve in Miami-Dade County (5, FTG). Plants were observed growing in the ecotone between pine rockland and rockland hammock.

In 1965, Olga Lakela collected Florida flatsedge on Chokoloskee Island in Collier County (29105, USF; 29324, USF). The plants were growing on shell mounds. Avery observed this population in 1980 (Avery’s Notes, 2 July 1980). The last hammock fragments on this island have been developed, and it is unlikely that this species persists there.

Major Threats: Exotic pest plant invasions; off-road bicycle use at R. Hardy Matheson Preserve.

Recommendations: • Map and monitor known stations on a regular basis. • Eliminate off-road bicycle use within area Florida flatsedge area at R. Hardy Matheson Preserve. • Consider introducing Florida flatsedge to other sites within its historical range, including Little Hamaca Park on Key West. • Consider restoring shell mounds hammocks on Chokoloskee Island and reintroducing Florida flatsedge.

Update: May 1, 2014. Since 2002, documented at a number of new sites. Down-ranked to imperiled in 2014 using updated NatureServe criteria.

Citation: Gann, G.D. 2014. Species Account Update, Cyperus filiformis, Floristic Inventory of South Florida Database Online. The Institute for Regional Conservation. Delray Beach, Florida.