IUCN threat status:

Not evaluated

Comprehensive Description

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Description

This perennial sedge consists of a tuft of low sterile shoots, from which arises one or more taller fertile shoots. The fertile shoots are leafy culms with terminal inflorescences; they are about 3-5' tall. The stout culms of fertile shoots are unbranched, bluntly 3-angled or terete (circular in cross-section), medium green, longitudinally veined, and glabrous. About 5-9 alternate leaves occur primarily along the lower half of each culm. The blades of these leaves are up to ½" (12 mm.) across and 2' long; they are ascending to widely spreading. The blades are medium green, glabrous, and longitudinally indented or furrowed. The leaf sheaths are medium green, longitudinally veined, glabrous, and closed. Sometimes small cross-veins interconnect the longitudinal veins on the culms and sheaths. The leaves of infertile shoots are similar to the leaves of fertile shoots, except the former are somewhat smaller than the latter and more evergreen. Each fertile culm terminates in an irregular compound cyme of spikelets spanning about 3-6" long and similarly across. This compound cyme has several ascending to drooping branches that are slender, green, and either glabrous or scabrous. These branches terminate in small clusters of 3-12 spikelets that are either sessile or pedicellate (usually the latter). One or more ascending to drooping branchlets originate from many of these spikelet clusters to terminate in either individual or secondary clusters of 2-10 spikelets that are either sessile or pedicellate (usually the latter). These branchlets are similar to the branches of the inflorescence, except they are more slender. Individual spikelets are about 4-7 mm. long, 2.5–3.5 mm. across, and more or less ovoid in shape; they are reddish brown, brown, or blackish brown at maturity and more or less covered with persistent woolly hairs. Each spikelet consists of a dense head of perfect florets and their scales in several overlapping series. Individual scales are about 1.5–2 mm. long, lanceolate to ovate in shape, and brown-membranous. Each perfect floret has a tripartite style, 3 stamens, and an ovary; each floret is partially hidden by its scale. At the base of the compound cyme, there are 3 or more large leafy bracts. Underneath the branched divisions of this cyme, there often occurs much smaller bractlets. The blooming period occurs from late summer to early fall, lasting about 1-2 weeks for a colony of plants. The florets are cross-pollinated by the wind. Afterwards, the florets are replaced by tiny achenes that are 0.5–1 mm. long and about one-half as much across. These achenes are pale brown, bluntly 3-angled, and pointed at both ends; each achene is surrounded by 6 long bristles (or hairs) 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.

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© John Hilty

Source: Illinois Wildflowers

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