IUCN threat status:

Not evaluated

Comprehensive Description

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Description

This perennial wetland plant is unbranched and 4-8' tall. The central culm is more or less erect and usually curved slightly to one side. This culm is dull green, terete, and soft from a spongy interior; it is up to 1/3" across at the base, becoming more slender upward. At the base, there are several membranous leaf sheaths that wrap around the culm; these sheaths lack leaf blades, or if such blades are present, then they are quite small and insignificant. Each fertile culm terminates in a single inflorescence spanning up to 6" long and 6" across. This inflorescence consists of a compound umbel of spikelets and a single basal bract about ½–3" long; this basal bract looks like a continuation of the culm. The branches and branchlets of the compound umbel are widely spreading and somewhat drooping; they are light green, flattened, and slender. Each branchlet terminates in either an individual spikelet or a dense cluster of 2-5 spikelets; the spikelets in each cluster are sessile or they have short pedicels. Each spikelet is about 6-8 mm. (1/4–1/3") in length and ovoid or ovoid-lanceoloid in shape, consisting of a compact head of perfect florets and their overlapping scales. The spikelets are brown to reddish brown and hairy in appearance because of the persistent bipartite styles (which become contorted and brown with age). The styles of the florets are white during the blooming period. The scales are ovate, brownish, and about 2.5–3.0 mm. long; each scale has a green central vein that may terminate in a very short awn. The blooming period occurs during the summer; the florets are wind-pollinated. Each fertile floret produces a single achene about 1.5–2.5 mm. long that is obovoid and brown; at the apex of each achene, there is a short slender beak. Each achene is surrounded by 4-6 bristles that are as long as or a little longer than the achene. The root system is fibrous and strongly rhizomatous. Dense colonies of vegetative plants are often formed from the rhizomes.

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© John Hilty

Source: Illinois Wildflowers

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