Carex crus-corvi    Shuttlw. ex Kunze

Raven's Foot Sedge 


MN Status:
delisted
Federal Status:
none
CITES:
none
USFS:
none

Group:
vascular plant
Class:
Monocotyledoneae
Order:
Cyperales
Family:
Cyperaceae
Life Form:
graminoid
Longevity:
perennial
Leaf Duration:
deciduous
Water Regime:
wetland
Soils:
silt, sand, muck
Light:
full shade, partial shade
Habitats:

(Mouse over a habitat for definition)


Best time to see:

  Foliage   Flower   Fruit  
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Carex crus-corvi Carex crus-corvi

Click to enlarge


Map Interpretation

Map Interpretation

  Synonyms

Carex bayardii

  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).

Carex crus-corvi has been collected only twice in Minnesota; first by J. H. Sandberg in Goodhue County in 1885 (not depicted on map) and later by Fassett and Hotchkiss in Wabasha County in 1926. Both of these collections were from bottomlands in the Mississippi River valley. Carex crus-corvi was listed as a special concern species in 1996.

  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.

  Description

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 cespitose (grows in clumps) with short rhizomes. The basal leaf sheaths from the previous year persist and are visible at the base of the plant. The leaf sheath is thin and pale-colored on the front, and red or purple dotted, sometimes strongly so. The culms are sharply three-angled and they are soft and easily crushed (Yatskievych 1999; Standley 2002). The species has large compound heads with the perigynia (casings around each seed) and the spikes clustered together in the head with little space in between them. The perigynium size, 6-8 mm (0.24-0.31 in.) long, and shape are distinctive. The body is somewhat triangular, with a thickened, spongy base. The beak is 2-3 times as long as the body and pointed, with 2 distinct teeth at the tip (Wheeler 1981; Yatskievych 1999; Standley 2002). Each pistillate spikelet has 2 stigmas and the spikes are relatively short, sessile, and contain both staminate and pistillate flowers (Yatskievych 1999).

  Habitat

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.

Both Minnesota collections for the species were made in August. In Wisconsin, the species blooms in June and fruits throughout July (Wisconsin DNR 2010). The best time to search for C. crus-corvi would be when it is flowering and fruiting, in June and July. It probably retains its seeds into late August (based on the Minnesota collections), so searches could continue through that time.

  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.

  References

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. . Accessed 5 January 2011.

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). . Accessed 31 August 2010.

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.