Vascular Plants of North Carolina
Account for Swan's Sedge - Carex swanii   (Fernald) Mackenzie
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(Fernald) Mackenzie
DistributionMountains and northern Coastal Plain. A wide gap separates the two areas of occurrence and probably is real.

N.S. to WI south to western SC and AR.
AbundanceFairly common in the southern Mountains but uncommon in the northern portions. Uncommon to fairly common in the northern Coastal Plain, but very rare to absent in the Piedmont (as it is also scarce in the southern Piedmont of VA).
HabitatMesic to dry mixed forests and forest openings; soils acidic to circumneutral. Has a great range of habitats in NC, though favoring mesic forests.
PhenologyFlowering and fruiting May-June.
IdentificationSwan's Sedge looks much like the common species Carex complanata and C. caroliniana, but female spikes of C. swanii are narrower (2-4 mm wide vs. 3.5-5 mm). Carex virescens has much longer female spikes (20-35 mm vs. 5-15 mm in C. swanii).
Taxonomic CommentsA synonym is C. virescens var. swanii.

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)None
State RankS3
Global RankG5
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