A good way to remember that the scales of this subspecies are more loosely arranged around the fruit than the closely related Cyperus lupulinus ssp. macilentus, which has scales that tightly clasp the fruit, is that the name lupulinus refers to the hop genus Lupulus which has inflated fruits. This subspecies may be undercollected because it very closely resembles the common subspecies macilentus.
There are seven existing populations but most of them are from specimens identified after collections took place so there is no detailed information about their locations or populations. There are 15 historical populations that have not been actively surveyed.
Not enough survey work has been done to understand short-term trends.
Long-term trends are not yet fully understood. There are about 15 historical records mostly from Long Island but not enough survey work has been done to relocate these occurrences nor to understand how common this species is now.
The species occurs in open sandy environments which are often used for recreation or development but not enough survey work has been done to fully understand current threats.
The open sandy habitat where this species grows needs to be protected from development and maintained in its open condition by preventing succession.
More herbarium work is needed to check specimens for correct identification. Habitat preference should be studied to understand why this species is not more common in a habitat that is common on Long Island. A search image needs to be refined to better locate this species among its closely related taxa.
More information on this species' habitat requirements is needed. In New York it has been collected from sandy soils at beaches, railroads, roadsides, and pastures (New York Natural Heritage Program 2007). Dry woods and fields (Gleason and Cronquist 1991).
In New York most collections of this species are from Long island, with a few collections from the Hudson Valley to as far north as Albany County.
Great Plains flatsedge is found from Massachusetts through the Upper Midwest and Ontario, as far west as Minnesota, and south to North Carolina to , extending west to Texas, Missouri and Colorado. It is also disjunct to Oregon and Idaho.
Great Plains flatsedge is a perennial flatsedge that grows from short tuberous rhizomes, from 1 to 5 dm tall. It has thin (.8-3.5 mm) leaves and a crowded, round, sessile spike. The leaves and bracts have scabrous margins. The spikelets are flattened and 2.5 to 5mm wide, and the achenes are trigonous, 1.4 to 2.2mm long, and about half as wide.
Fruiting individuals are needed to identify this plant.
The other subspecies of Cyperus lupulinus, C. luplinus ssp. macilentus, is more widely distributed in New York, has 3-7 floral scales whose margins clasp the achenes, whereas C.lupulinus ssp. lupulinus has 5 -22 floral scales, not touching the achenes. C. hougtonii and C. schweinitzii each tend to have shorter achenes and scales (Voss 1972).
This species fruits in late July, the fruits persistent into fall.
The time of year you would expect to find Great Plains Flat Sedge fruiting in New York.
Great Plains Flat Sedge
Cyperus lupulinus ssp. lupulinus None
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.
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. 2021. New York Natural Heritage Program Databases. Albany, NY.
Voss, E.G. 1972. Michigan Flora, Part I. Gymnosperms and Monocots. Cranbrook Institute of Science Bulletin 55 and the University of Michigan Herbarium. Ann Arbor. 488 pp.
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
Weldy, Troy W. and David Werier. 2005. New York Flora Atlas. [S.M. Landry, K.N. Campbell, and L.D. Mabe (original application development), Florida Center for Community Design and Research. University of South Florida]. New York Flora Association, Albany, NY. Available on the web at (http://newyork.plantatlas.usf.edu/).
Information for this guide was last updated on: January 18, 2008
Please cite this page as:
New York Natural Heritage Program. 2021. Online Conservation Guide for Cyperus lupulinus ssp. lupulinus. Available from: https://guides.nynhp.org/great-plains-flatsedge/. Accessed May 17, 2021.