Description: This native
perennial sedge is 1-2' tall, forming loose tufts of both fertile and infertile
shoots that are erect to ascending. The culms are 3-angled, light to medium
green, and glabrous and or sparsely pubescent. About 3-5 alternate leaves
develop along each culm. The ascending to widely spreading leaf blades are up
to 12" long and 4 mm. across; they are medium green and sparsely pubescent. The
leaf sheaths are relatively tight and moderately pubescent. At the junction of
each blade and sheath, there is a short-membranous ligule that is longer than
wide. Each fertile culm terminates in an inflorescence consisting of a terminal
spikelet at the apex, 1-3 lateral spikelets, and their leafy bracts. The
terminal spikelet is about ½–¾" long, short-cylindrical in
shape, and gynecandrous; it has pistillate florets and scales along the upper
three-fourths of its length, while staminate florets and scales are below. The
lateral spikelets are similar in appearance to the terminal spikelet, except
they are a little shorter and they have only pistillate florets and scales. The
peduncle of each spikelet is slender, short, and straight. At the base of the
lowest peduncle, there is a leafy bract as long or longer than the
inflorescence, while the remaining bracts are much smaller in size. In each
spikelet, the perigynia of the pistillate florets are ascending and densely
packed together. Each perigynium (a bladder-like sac covering the developing
achene) is about 2.0 mm. long and 1.0–1.5 mm. across; it is light green
(while immature), densely pubescent, obovoid-ovoid, bluntly 3-angled, and
nearly beakless. The membranous pistillate scales are about 2.0 mm. long, 1.0
mm. across, and ovate with an awn-like tip. The blooming period occurs from
late spring to early summer and lasts about 2 weeks. The florets are
wind-pollinated. The achenes are about 1.5 mm. long. The root system is fibrous
and rhizomatous.
Cultivation: The
preference is dappled sunlight to light shade, mesic to dry conditions, and
rocky or sandy soil containing some decaying organic matter (e.g., fallen
leaves). This sedge is usually found where the ground vegetation is rather
sparse.
Range & Habitat: Swan's
Sedge is scattered across most areas of Illinois, except the NW section of the
state (see
Distribution
Map). It is an uncommon sedge. Habitats include rocky upland woodlands,
sandy savannas, and sandy swamps (in NE Illinois). This sedge is often found in
wooded areas where oak trees
are present and the shade of the overhead canopy is not
too dense.
Faunal Associations: In
general, sedges (Carex spp.) are a source of food to many kinds of insects,
birds, and other animals. Which species are likely to feed on a particular
sedge varies with its habitat. Some insect feeders include: the caterpillars of
the butterflies Satyrodes appalachia (Appalachian Brown) and
Satyrodes eurydice (Eyed Brown), which feed on the foliage; the larvae
of several billbugs (Sphenophorus spp.), which bore through the stems; and the
seed bugs Cymus angustatus and Oedancala dorsalis. Some bird
species eat the seeds of sedges in upland woodlands; these include the Wild
Turkey, Bobwhite, chicks of the Ruffed Grouse, Cardinal, Eastern Towhee, and
several sparrows. The seeds of such sedges are also eaten by the Fox Squirrel
and Gray Squirrel. In contrast, White-Tailed Deer rarely browse on the foliage
because they prefer broad-leaved plants.
Photographic Location: A rocky upland woodland at
the Portland Arch in west-central Indiana.
Comments: This is one of the more hairy sedges in
Illinois. Swan's Sedge is very similar to Carex virescens (Hairy-Fruited
Sedge) and it was considered a variety of the latter species at one time.
Swan's Sedge differs primarily by its shorter spikelets (¾" long or
less); it also has leaf blades that are slightly more narrow and its habit of
growth tends to be more erect. Two other hairy sedges are Carex
hirsutella (Hairy-Leaved Sedge) and Carex hirtifolia (Hairy Sedge);
these sedges also occur in upland woodlands. Hairy-Leaved Sedge differs from
Swan's Sedge by its hairless perigynia, while the terminal spikelet of Hairy
Sedge consists entirely of staminate florets and scales. Another common name of
Carex swanii is Savanna Sedge.