In New York this flatsedge has only ever been collected around the New York City area, mostly in the late 1800s and early 1900s. It was seen a few times after World War II up until 1950, but not collected again until the 1980s in the serpentine areas of Staten Island. These records represent the most northern extension of the species along the Atlantic coast.
There are currently believed to be five existing populations, but two of them have not been seen since the 1980s and may have been shaded out by natural succession. They may still persist in the seed bank. Only one population has more than 100 plants. There are two old records from Staten Island which have not been resurveyed and there are nine more records which are now considered extirpated.
Short-term trends appear stable although a couple of populations are probably present only in the seed bank, waiting for a disturbance to facilitate germination.
This plant has declined severely over the last 100 years because of the development of New York City, especially on Staten Island where it was once considered relatively common. Remaining populations are small and long-term trends will probably continue downward.
Current populations are threatened by direct human disturbance from development and subsequent human use of nearby natural areas where plants are trampled. Lack of management has also allowed succession to eliminate the vegetative stems of two populations although they may still be in the seed bank.
This species needs disturbance to reduce competition from woody plants or more aggressive herbaceous plants but too much direct disturbance to the plants will reduce or eliminate the population. Its habitat could be disturbed in the non-growing season to open it up for seed germination and colonization but direct disturbance should be prevented during the growing season.
Research is needed to understand habitat requirements and management practices to protect and augment populations.
The few New York records of this species are from open, disturbed areas, including serpentine grasslands, meadows kept open by fire and other disturbance, and the upland edge of a high salt marsh (New York Natural Heritage Program 2010). Disturbed, sunny sites, in mesic places, well-drained soils....predominantly an inland species of roadsides, pastures, and other disturbed ground (FNA 2002). Dry woods and fields (Gleason & Cronquist 1991). Sandy swamps, ditches, open woods and barrens (Fernald 1970).
This species is known from the New York City area where it is currently known from the Bronx and Staten Island but considered extirpated from Manhattan and Queens. There is also one historical record from the Yonkers area of Westchester County which is probably also extirpated.
This flatsedge is most common from southeastern Pennsylvania south to northern Florida and west to Texas, Missouri, and Kansas. It reaches its northeastern range limit in southern New England and New York. There are a few disjunct populations from central Wisconsin, northern Illinois, Ontario, and in northern Ohio. It also occurs in the West Indies.
Globose Flatsedge is a grass-like perennial herb, growing singly or in loose clumps, and up to 30 to 100 cm tall. Its stems are 3-sided and smooth. The leaves are flat or V-shaped, 3 to 9 mm wide, with rough edges. The infloresence is exceeded by the lowest bract, and consists of 1 or 2 sessile, terminal round or egg-shaped spikes, each with 3 to 12 ascending rays. Each spike in turn contains many spikes, radiating in all directions, each with 1 to 3 flowers subtended by persistent straw-colored to brownish scales 3 to 7.5 mm long. The fruit are brown, pitted, oblong achenes, about half as long as the flower scales (FNA 2002, Gleason and Cronquist 1991).
Entire plants with mature fruit are needed for identification.
The New York flatsedge species Cyperus echinatus is most similar to C. retrorsus. C. retrorsus differs by having smaller spikelets, shorter flowering scales (1.8 to 2.5 mm long versus 3 to 4.5 mm for C. echinatus) and anthers, and shorter, relatively fatter achenes (1/3 to 1/2 as wide as long, versus no more than 1/3 as wide as long for C. echinatus) (FNA 2002, Gleason and Cronquist 1991).
Globose Flatsedge's fruits mature in late July and may persist through September.
The time of year you would expect to find Globe Flat Sedge fruiting in New York.
Globe Flat Sedge
Cyperus echinatus (L.) Wood
Flora of North America Editorial Committee. 2002. Flora of North America, North of Mexico. Volume 23. Magnoliophyta: Commelinidae (in part): Cyperaceae. Oxford University Press, New York. 608 pp.
Fernald, M. L. 1950. Gray's manual of botany. 8th edition. Corrected printing (1970). D. Van Nostrand Company, New York. 1632 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.
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. 2023. 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. 2023. Online Conservation Guide for Cyperus echinatus. Available from: https://guides.nynhp.org/globose-flatsedge/. Accessed January 30, 2023.