Vascular Plants of North Carolina
Account for Kidney-shape Sedge - Carex reniformis   (L.H. Bailey) Small
Members of Cyperaceae:
Members of Carex with account distribution info or public map:
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Section 5 » Order Cyperales » Family Cyperaceae
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Author(L.H. Bailey) Small
DistributionCoastal Plain, reported in only five counties. Reports from Bladen, Pender, and Sampson counties need ID check, as specimens have not been seen (these are records from Carolina Vegetation Survey plots). In 2023 Eric Ungberg checked specimens at NCU and agrees with ID of the Johnston County sheet, but suggests that the Wake County sheet may be C. longii; a second determination is warranted.

VA, IL, and OK, south to northwestern FL and TX.
AbundanceApparently rare. The two specimen records are both historical, and thus the basis for NCNHP's S1 (extant but very rare) State Rank lies on the assumption of correctness of the CVS records. This is a State Threatened species.
HabitatFloodplain forests (brownwater and blackwater), marshes.
PhenologyFlowering and fruiting May-June.
IdentificationKidney Sedge is often confused with C. alata, due to similarly wide perigynia. It differs in female scales obtuse at the tip (vs. acuminate or awned up to 0.8 mm in C. alata).
Taxonomic CommentsNone

The genus Carex is the largest in North America, and among the largest in the world. In temperate and boreal regions, Carex is often the dominant or co-dominant ground layer in many habitats. Seeds (achenes) are valuable food for birds and small mammals, while foliage is used by birds and mammals to make nests and as food by mammals. Species of Carex often look vastly different from one another -- spikes erect vs. drooping, tiny inflorescence vs. whopping, culms leafy vs. naked, perigynia beaked vs. beakless, stems densely bunched vs. single, etc. The genus has been divided into many sections (or groups), based on shared characters; some taxonomists have suggested that these be different genera, but that proves unworkable (so far). All Carex share the feature of a perigynium (an outer covering) which completely surrounds the achene (seed). This covering may fit tightly or loosely (like a small bladder), depending on which group or species. Details of perigynia shape, ornamentation, presence and size of beak, number of striations (or veins) are all important ID features. In recent years Rob Naczi and colleagues have stressed the importance of arrangement of perigynia -- whether spiral (3+ ranks) or distichous (2-ranked) -- and have named a number of new species as well as split off some older synonyms. Therefore, RAB's (1968) key, excellent for its time, can only be used in a general way today. Members of some sections of Carex are difficult to key out (notably Ovales, Laxiflorae, Griseae); this is in part due to variation among individuals of a species, or failings of the key. FNA has drawings of most species and some species may be found in two or more places within a key, to acount for variability. New species to NC, and new to science(!), continue to be found in NC.
Other Common Name(s)Kidney Sedge, Reniform Sedge
State RankS1
Global RankG4?
State StatusT
US Status
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