Sedge family (Cyperaceae)
Description: This 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 to 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: The native 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, wooded slopes, upland savannas, and sandy savannas. 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: This sedge occurs primarily in thin upland woodlands where there is reduced competition from other kinds of ground vegetation. Insects that feed on sedges (Carex spp.) in this kind of habitat include larvae of the leaf-miner moths Elachista argentosa and Elachista madarella, and such aphids as Carolinaia caricis, Iziphya albipes, Iziphya flabella, and Vesciculaphis caricis. Some bird species eat the seeds of sedges in upland woodlands; they include such species as the Wild Turkey, Bobwhite, immature 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.