Carex crus-corvi
Raven's-foot sedge
Image of Carex crus-corvi

Photo by Bradford S. Slaughter 

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Key Characteristics

Clumped sedge of wet floodplain forests and buttonbush depressions; sheaths with numerous tiny dark spots; culms stout but easily compressed; perigynia flattened, large (8 mm long), with broad spongy base and long prominent beak.

Status and Rank

  • State Status: E
  • State Rank: S1
  • Global Rank: G5


County NameNumber of OccurrencesYear Last Observed
Distribution map for Carex crus-corvi

Updated 5/15/2018. Information is summarized from MNFI's database of rare species and community occurrences. Data may not reflect true distribution since much of the state has not been thoroughly surveyed.


Very rare and local, persisting at least in southernmost Michigan in wet depressions in forested floodplains.

Natural Community Types


For each species, lists of natural communities were derived from review of the nearly 6,500 element occurrences in the MNFI database, in addition to herbarium label data for some taxa. In most cases, at least one specimen record exists for each listed natural community. For certain taxa, especially poorly collected or extirpated species of prairie and savanna habitats, natural community lists were derived from inferences from collection sites and habitat preferences in immediately adjacent states (particularly Indiana and Illinois). Natural communities are not listed for those species documented only from altered or ruderal habitats in Michigan, especially for taxa that occur in a variety of habitats outside of the state.

Natural communities are not listed in order of frequency of occurrence, but are rather derived from the full set of natural communities, organized by Ecological Group. In many cases, the general habitat descriptions should provide greater clarity and direction to the surveyor. In future versions of the Rare Species Explorer, we hope to incorporate natural community fidelity ranks for each taxon.

Associated Plants

Trees: Acer saccharinum (silver maple), Carya laciniosa (shellbark hickory), Celtis occidentalis (hackberry), Fraxinus pennsylvanica (green ash), Juglans nigra (black walnut), Platanus occidentalis (sycamore), Ulmus americana (American elm).

Shrubs and Vines: Cephalanthus occidentalis (buttonbush), Toxicodendron radicans (poison-ivy), Vitis riparia (riverbank grape).

Herbs: Ambrosia trifida (giant ragweed), Arisaema dracontium (green dragon), Asclepias incarnata (swamp milkweed), Carex davisii, C. grayi, C. lupulina, C. muskingumensis, C. stipata, C. tribuloides, Elymus virginicus (Virginia wild-rye), Iris virginica (southern blue flag), Laportea canadensis (wood nettle), Leersia oryzoides (cut grass), Persicaria lapathifolia (nodding smartweed), Rumex verticillatus (water dock), Saururus cernuus (lizard's-tail), Symphyotrichum ontarionis (Lake Ontario aster), Teucrium canadense (wood-sage), Viola sororia (common blue violet).


Primarily requires conservation of habitat and hydrological regime, including fluctuating water tables. It may also be susceptible to direct and indirect impacts from timber harvesting.

General Survey Guidelines

Random meander search covers areas that appear likely to have rare taxa, based on habitat and the judgement of the investigator.

Survey Methods

Page Citation

Michigan Natural Features Inventory. 2007. Rare Species Explorer (Web Application). Available online at [Accessed Aug 18, 2018]


Survey References

Technical References

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