Sedge family (Cyperaceae)
Description: This native perennial plant consists of a clump of low vegetative shoots, from which arises one or more flowering stalks about 3-5' tall. The stout culms of the these flowering stalks are unbranched, bluntly 3-angled or terete (round in cross-section), medium green, and glabrous. Each culm has 5-9 alternate leaves along its length. The blades of these leaves are up to ½" (12 mm.) across and 2' long; they are ascending to widely spreading. Each blade is medium green, glabrous, and slightly indented along the middle of its length. The leaf sheaths are medium green, glabrous, and closed. The leaves of the low vegetative shoots are similar to the leaves of the flowering stalks, except the former are somewhat smaller than the latter and more evergreen.
Each fertile culm terminates in a compound umbel of spikelets spanning about 4-6" long and wide. This compound umbel has many drooping branchlets that are slender, glabrous, and green. The outer branchlets terminate in small clusters of 3-12 sessile (or nearly sessile) spikelets. Each ovoid spikelet is about 5-6 mm. long and 3 mm. across; it becomes reddish brown and woolly at maturity, consisting of a dense head of perfect florets, scales, and bristles. Each floral scale is about 2 mm. long, lanceolate to ovate, and brown-membranous; each floret has a tripartite style, 3 stamens, and a developing ovary. At the base of the compound umbel, there are 3 or more large leafy bracts. Underneath each branched division of this umbel, there often occurs much smaller brown bractlets. The blooming period occurs from late summer to early fall. The florets are wind-pollinated. Each fertile floret is replaced by a tiny achene less than 1 mm. long. This achene is pale brown, 3-angled, and pointed at both ends; it is surrounded by 6 long bristles that are reddish brown, curly, and persistent. It is the exerted bristles of the many achenes in the spikelets that provide them with their woolly appearance. The root system is fibrous and short-rhizomatous. Wool Grass often forms colonies of plants.
Cultivation: The preference is full or partial sun, wet to moist conditions, and soil that is muddy, sandy, or gravelly. Shallow water is tolerated. The easiest way to start new plants is by division of the vegetative shoots.
Range & Habitat: Wool Grass is occasional to locally common throughout Illinois (see Distribution Map). It has been collected less often in the central section of the state. Habitats consist of both sandy and non-sandy wetlands, including marshes, swamps, sloughs (seasonal streams), sedge meadows, gravelly seeps, and borders of ponds. This species is somewhat variable across its range.
Faunal Associations: Several leaf beetles (Donacia spp. & Plateumaris spp.) feed on the foliage of Scirpus spp. (Bulrushes), while the seed bugs Cymus luridus, Cymus angustatus, and Cymus discors feed on the seedheads. The latter two seed bugs have been observed on Wool Grass specifically. The caterpillars of Euphyes dion (Dion Skipper) and the moth Ledaea perditalis (Lost Owlet) also feed on Wool Grass. Bulrushes are an important source of food and cover to many vertebrate animals. Many species of ducks and other wetland birds feed on the seedheads of bulrushes; Canada Geese and the Trumpeter Swan also eat the foliage. See the Bird Table for a listing of these species. Because Wool Grass and other bulrushes often form dense colonies of plants, they provide good nesting habitat for various species of wetland birds. Muskrats eat both the foliage and rhizomes of bulrushes, while the Meadow Vole eats the seedheads.
Photographic Location: A sandy marsh in Vermillion County, Illinois.
Comments: The common name of this species is misleading because it isn't a member of the Grass family (Poaceae). Instead, it is a member of the Sedge family (Cyperaceae), like other Scirpus spp. To make matters even more confusing, these species are collectively referred to as 'Bulrushes,' even though they are not members of the Rush family (Juncaceae). Notwithstanding such problems with nomenclature, Wool Grass is one of the more attractive bulrushes, particularly during the early fall when its spikelets become woolly reddish brown. It can be distinguished from similar species by considering the following features: 1) Wool Grass has leafy culms, as opposed to leafless culms, 2) its spikelets are reddish brown and exceptionally woolly at maturity, 3) its inflorescence is a drooping compound umbel at the apex of the culm, and 4) it has small clusters of 3-12 sessile or nearly sessile spikelets on the terminal branchlets of each umbel, as opposed to individual spikelets. Some local populations of Wool Grass have atypical spikelets that are a darker shade of brown or more cylindrical in shape than what is typically encountered. Such variations may be the result of hybridization between similar species.