Wool Grass - Marsh Bulrush
Scirpus cyperinus (Lannaeus) Kunth
Cyperaceae (Sedge) Family

Wool Grass is a perennial sedge consisting of a tuft of low sterile shoots, from which arises one or more taller fertile shoots. The fertile shoots are leafy hollow stems with terminal flowers; they are about 3 to 5 feet tall. The stout stems of fertile shoots are unbranched, bluntly 3-angled or circular in cross-section, medium green, longitudinally veined, and smooth. About 5 to 9 alternate leaves occur primarily along the lower half of each stem.

The leaf blades are up to ½ inch across and 2 feet long; are ascending to widely spreading. The blades are medium green, smooth, and indented or furrowed. The leaf sheath is medium green, veined, smooth, and closed. Sometimes small cross-veins interconnect the longitudinal veins on the stems 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.

The spikelets consist of a dense head of bisexual florets in several overlapping series. Individual florets are about 1.5 to 2 mm long, lanceolate to ovate in shape, and brown-membranous. Each floret has a tripartite style, 3 stamens, and an ovary. At the base of the compound cyme, there are 3 or more large leafy bracts.

Underneath the branched divisions, there often occurs much smaller bractlets. The blooming period occurs from late summer to early fall, lasting about 1 to 2 weeks for a colony of plants. The florets are cross-pollinated by the wind.

Fruit is tiny achenes that are 0.5 to 1 mm. long and about one-half as much across. These achenes are pale brown, bluntly 3-angled, and pointed at both ends; surrounded by 6 long bristles (or hairs) that are reddish brown, curly, and persistent.

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