The specific epithet mitchelliana was named in honor of Eisha Mitchell who lived from 1793 to 1857 (Fernald 1970).
There are only five known populations on Long Island, but more populations are suspected. A handful of historical locations still need to be surveyed. This is a plant of coastal wetlands that is confused with Carex crinita and Carex gynandra. Range-wide fewer than 100 populations are known, all restricted to the Atlantic and Gulf Coasts. This plant is threatened by invasive species, particularly Phragmites, and habitat alterations.
One population is considered to have become extirpated in the past twenty years due to succession. Another populations was not seen on a recent survey but may still be extant. The four other populations that are known from recent survey work are very small in number, ranging from 2 to 20 plants. Therefore, the short term trends indicate that this species is declining.
One population is believed to be extirpated. Another population was not seen during recent survey work but may still be extant. There are about eight populations that are only known from historical records. These populations have not been surveyed in recent years and may still be extant. This species is similar to other closely related species and may be overlooked although in general, C. mitchelliana is local and uncommon throughout its range. Overall, long term trends are not clear but indicate at least some decline.
At least a couple of populations appear to be mowed periodically. An improper mowing regime might threaten these populations. Residential development is also a potential threat.
Unprotected sites should be secured from future development.
All historical populations should be searched for to determine if they are still extant. Ongoing monitoring of all extant populations is needed at least every five years because populations are small. Surveys to find new populations should also be conducted. The impacts of mowing on populations should be assessed.
Carex mitchelliana occurs in wet meadows and sedge meadows, swamps, and seeps. It is known from along stream and pond edges sometimes near brackish water and in boggy ground (New York Natural Heritage Program 2006). Swamps, floodplain forests, wet meadows, stream edges, margins of lakes and ponds, roadside ditches (Standley et al. 2002). Swamp forests and wet thickets and meadows (Gleason and Cronquist 1991). Swales, swamps, and wet woods (Fernald 1970).
Carex mitchelliana is mostly restricted to Long Island including one population on the eastern edge of Queens. There is also a historical population known from Westchester.
Carex mitchelliana occurs predominately along the Atlantic and Gulf coastal plains of the eastern United States. It occurs from Massachusetts and New York south to Florida and west to Mississippi, Tennessee, and Kentucky (Standley et al. 2002).
Mitchell's sedge is a tufted, grass-like perennial. It has strap-like leaves that are 3-8 mm wide. Stems 40-140 cm tall arise from the tuft of leaves at the base of the plants. Leaves occur along these stems and a narrowly cylindrical cluster of tiny male flowers occurs at the apex of the stems. Secondary branches occur towards the apex of the stems and are terminated by additional flower/fruit clusters (spikes) which droop. These spikes are predominately composed of female flowers which mature into fruits (perigynia) 2.5-3.9 mm long (Standley et al. 2002).
Carex mitchelliana is a cespitose perennial. Leaf blades are 3-8 mm wide and the sheaths are scabrous. Culms are 40-140 cm tall. There are 2-4 lateral drooping pistillate spikes which often have some staminate florets at their apices. There is one terminal staminate spike and sometimes a second staminate spike proximal to the terminal spike. The bodies of the pistillate scales are truncate at their apices and have scabrous awns projecting beyond their apices. Perigynia are scarcely inflated, loosely enclose the achenes, and are papillose over the entire surface. The achenes are not constricted (Bruederle et al. 1989, Standley et al. 2002).
Mature or almost mature perigynia as well as lower leaf sheathes are needed to identify this species. Therefore, full plants should be collected when C. mitchelliana has mature or almost mature perigynia.
Carex crinita and C. gynandra are both very similar and careful attention is needed to correctly identify C. mitchelliana. Carex crinita (both varieties) differs from C. mitchelliana in having glabrous and smooth leaf sheaths; perigynia ovoid with papillae short and not covering the entire surface; apices of bodies of pistillate scales retuse; and achenes constricted or not vs. minutely pubescent and scabrous leaf sheaths; perigynia obovoid with papillae longer and covering the entire surface; apices of bodies of pistillate scales truncate (sometimes retuse); and achenes not constricted for C. mitchelliana (Bruederle et al. 1989, Standley et al. 2002).
Carex gynandra differs from C. mitchelliana in having perigynia with papillae short and not covering the entire surface; apices of bodies of pistillate scales acuminate; and achenes constricted vs. perigynia with papillae longer and covering the entire surface; apices of bodies of pistillate scales truncate; and achenes not constricted for C. mitchelliana (Bruederle et al. 1989, Standley et al. 2002).
Carex mitchelliana starts producing perigynia in early to mid June. These mature and persist through August although in the later part of this season they are shedding easily. Therefore the best time to survey for this species is from mid June till late July.
The time of year you would expect to find Mitchell's Sedge fruiting in New York.
Carex mitchelliana M.A. Curtis
Carex mitchelliana was first described in 1843. Since that time, this taxon has been variously lumped under other taxa, treated as a variety, or treated as a distinct species. Carex mitchelliana is currently recognized at the species level based on morphological and micromorphological characters, biogeography, and allozyme data (Bruederle et al. 1989). Mitchell and Tucker (1997) placed the name C. gynandra var. mitchelliana (Curtis) Gleason as a synonym under C. mitchelliana. This name is an error as Gleason transferred the taxon to C. crinita as C. crinita var. mitchelliana (Gleason and Cronquist 1963). Carex mitchelliana is in section Phacocystis. It had previously been placed in section Cryptocarpae but that section is no longer considered distinct (Standley et al. 2002).
Standley, L.A., J. Cayouette, and L. Bruederle. 2002. Carex Linnaeus sect. Phacocystis Dumortier. Pages 379-401 in Flora of North America Editorial Committee (editors), Flora of North America, North of Mexico, Volume 23, Magnoliophyta: Commelinidae (in part): Cyperaceae. Oxford University Press, New York, NY, USA. 608pp + xxiv.
Bruederle, L.P., D.E. Fairbrothers, and S.L. Hanks. 1989. A systematic circumscription of Carex mitchelliana (Cyperaceae) with reference to taxonomic status. Amer. J. Bot. 76: 124-132.
Fernald, M.L. 1950. Gray's manual of botany. 8th edition. D. Van Nostrand, New York. 1632 pp.
Gleason, H.A. and A. Cronquist. 1963. Manual of the Vascular Plants of Northeastern North America and Adjacent Canada. Van Nostrand Reinhold Co., New York.
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.
Mitchell, Richard S. and Gordon C. Tucker. 1997. Revised Checklist of New York State Plants. Contributions to a Flora of New York State. Checklist IV. Bulletin No. 490. New York State Museum. Albany, NY. 400 pp.
New York Natural Heritage Program. 2020. 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
Information for this guide was last updated on: May 31, 2006
Please cite this page as:
New York Natural Heritage Program. 2020. Online Conservation Guide for Carex mitchelliana. Available from: https://guides.nynhp.org/mitchells-sedge/. Accessed September 27, 2020.