IUCN threat status:

Not evaluated

Comprehensive Description

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Description

This perennial sedge is about 1½–3' tall, consisting of a tuft of leaves and flowering culms. The erect to ascending culms are light green to green, 3-angled, glabrous, and rather spongy toward the base, becoming more slender at the apex where the inflorescence occurs. Alternate leaves are produced from both fertile and infertile shoots. The leaf blades are up to 2' long and ½" (12 mm.) across; they are light green to green, glabrous, and linear in shape. The leaf blades have a tendency to arch away from their culms; the larger blades are conspicuously furrowed along their central veins. The leaf sheaths are light green, longitudinally veined, and glabrous. The culm of a fertile shoot terminates in an inflorescence consisting of a terminal staminate spikelet (less often 2-3 staminate spikelets) and 2-7 pistillate spikelets. The narrow staminate spikelet is up to 4" long, light to dark brown (after releasing its pollen), and somewhat flattened; it can be nearly sessile, short-stalked, or long-stalked. The pistillate spikelets are up to 3½" long and 1¼" across; they are oblongoid-cylindrical in shape and densely crowded with the inflated perigynia of the pistillate florets. These perigynia are mostly ascending; the lower perigynia are more widely spreading. Initially, the pistillate spikelets are light green to yellowish green, but they become yellowish brown to brown with maturity. The pistillate spikelets usually occur in a loose cluster on short slender peduncles. The perigynia are up to 15 mm. (2/3") long and 6 mm. (¼") across; they are lanceolate-ovoid in shape, tapering to long narrow beaks. There are several fine longitudinal veins along the outer surface of each perigynium. The pistillate scales are smaller in size than the perigynia; they are lanceolate, tapering gradually into awned tips. Immature pistillate scales have green central veins and translucent margins; they become more brown at maturity. The blooming period occurs from late spring to mid-summer (rarely later), lasting about 1-2 weeks. The florets are cross-pollinated by wind. At this time, each pistillate floret has 3 curly white stigmata that are exerted from the beak of its perigynium. About one month after the blooming period, the inflated perigynia disarticulate from the pistillate spikelets; they have the capacity to float on water, distributing the achenes to new areas (there is one achene per perigynium). The achenes are about 3 mm. long and 3 mm. across; they are hexaploid in shape and sharply angular (shaped like 6-sided diamond crystals); they are often slightly knobby where 3 edges meet at lateral corners, and their sides are often slightly concave. The achenes are glabrous and, depending on their maturity, light green to brown. At the apex of each achene, there is a persistent style that is coiled or curved near its base; this style is longer than the achene. The root system is fibrous and rhizomatous. Occasionally, clonal offsets are produced from the rhizomes.

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Creative Commons Attribution Non Commercial 3.0 (CC BY-NC 3.0)

© John Hilty

Source: Illinois Wildflowers

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