Carex crus-corvi Shuttlw. ex Kunze
Raven's Foot Sedge
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Basis for Former Listing
Carex crus-corvi is distributed along drainages of the Mississippi River and also along the southeast coastal plain (Standley 2002). Range-wide it is found in wetland habitats and along floodplains. Carex crus-corvi tends to be rare on the edges of its range (to the north, west, and east) and is considered critically imperiled in Wisconsin, Nebraska, Ontario, Virginia, and North Carolina (NatureServe 2011). Minnesota represents the northwestern-most limit of the species' range (Wheeler 1981).
Basis for Delisting
When C. crus-corvi was designated a special concern species, some potential habitat still remained to be surveyed. Despite botanical inventory work in Goodhue and Wabasha counties and some efforts to specifically search for this species, no remnant populations of C. crus-corvi have been discovered. The loss of this species in Minnesota may be the result of the drastic alteration of its habitat caused by the extensive lock and dam system constructed on the Mississippi River in the 1930s. Carex crus-corvi is now considered extirpated from Minnesota. Therefore, special concern status is no longer necessary and the species was delisted in 2013.
Carex crus-corvi is a perennial sedge that reaches 1 m (3.3 ft.) in height. The stem is stout and triangular and the linear leaves are 5-10 mm (0.20-0.39 in.) wide. Stems and leaves grow together in clumps. Seed heads are at the tips of the stems and have a bristly appearance, hence the specific epithet crus-corvi, meaning "crow spur" (Wisconsin DNR 1981).
Carex crus-corvi is known range-wide from swamps, sloughs, bottomland forests, bottomland prairies, banks of rivers and streams, and also ditches (Yatskievych 1999). In Goodhue County, Minnesota, it was collected in wet places near Red Wing, but the exact location is unknown. In Wabasha County, it was collected in a shady swale near a slough near Weaver, Minnesota (Rosendahl and Moore 1947). In Wisconsin, the species is also rare and grows in ephemeral woodland ponds where it is associated with Fraxinus pennsylvanica (green ash), Acer rubrum (red maple), Glyceria grandis var. grandis (tall manna grass), and Carex tuckermanii (Tuckerman's sedge). Potential native plant community classes in Minnesota include southern floodplain forest, southern terrace forest, northern bulrush-spikerush marsh, and southern wet ash swamps.
Biology / Life History
Carex crus-corvi is a perennial sedge that is wind pollinated and reproduces mostly by seed; any rhizomes it has are short, so it likely has little capacity to reproduce vegetatively. Dispersal mechanisms are not known, but because of its habitat, the perigynia could be transported on spring floodwaters.
Conservation / Management
If C. crus-corvi were rediscovered in Minnesota, its habitat would need to be protected from development and invasive species. Further efforts could be made to relocate the species through systematic searches of appropriate habitat, especially near historic locations.
Conservation Efforts in Minnesota
Because there are no known extant populations of C. crus-corvi in Minnesota, no conservation efforts have been directed towards this species.
Minnesota Department of Natural Resources. 2012. Statement of need and reasonableness. Minnesota Department of Natural Resources. Division of Ecological and Water Resources. St. Paul, Minnesota. 337 pp.
NatureServe. 2011. NatureServe Explorer: An online encyclopedia of life [web application]. Version 7.1. NatureServe, Arlington, Virginia.
Rosendahl, C. O., and J. W. Moore. 1947. A new variety of Sedum rosea from southeastern Minnesota and additional notes on the flora of the region. Rhodora 49:197-202.
Standley, L. A. 2002. Carex sect. Vulpinae. Pages 273-278 in Flora of North America Editorial Committee, editors. Flora of North America north of Mexico. Volume 23. Oxford University Press, New York, New York.
Wheeler, G. A. 1981. A study of the genus Carex in Minnesota. Dissertation, University of Minnesota, St. Paul, Minnesota. 501 pp.
Wisconsin Department of Natural Resources. 1992. Endangered resources handbook 1724.5. Wisconsin Department of Natural Resources, Madison, Wisconsin. 283 pp.
Wisconsin Department of Natural Resources [WIDNR]. 2010. Ravenfoot Sedge (Carex crus-corvi).
Yatskievych, G. 1999. Steyermark's flora of Missouri. Second edition, Volume 1. Missouri Department of Conservation, Jefferson City and Missouri Botanical Garden Press, St. Louis, Missouri.