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Northern Prairie Wildlife Research Center

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Aquatic and Wetland Vascular Plants of the Northern Great Plains

62. Cyperaceae, the Sedge Family

5. Elocharis R. Br. -- Spikesedge, spikerush

2. Eleocharis compressa Sulliv. -- Flatstem spikesedge

Sparsely tufted perennial from stout black rhizomes; culms flattened (especially obvious toward the base), 1.5-4 dm tall, angled by longitudinal grooves, 0.5-1 mm wide; sheaths reddish or purplish at the base, firm, slightly oblique at the orifice. Spikelets ovoid, blunt, 4-9 mm long, 3-4 mm thick; lowermost scale sterile, encircling the culm; floriferous scales many, reddish-brown on the sides, with a pale midvein, ovate-lanceolate, 2-3 mm long, white-hyaline on the margins, bifid or lacerate at the tip with age; perianth usually lacking or of 1-4 bristles, these reaching to more than 1/2 the length of the achene; styles trifid. Achenes golden-yellow to brown, warty or wrinkled on the surface, unequally trigonous, 0.75-1.1 mm long, 2/3 to fully as wide, often persistent after the scales have fallen; tubercle deltoid to depressed-deltoid, to 1/4 the length of the achene, constricted at the attachment to the achene. Jun--Aug. Low prairie, wet meadows and seepage areas; frequent, but easily overlooked or dismissed for more common spp.; (Que. and NY to Sask., s to VA, GA, AL, MO, TX and CO).

Reports of the similar E. verrucosa (Svens.) Harms [= E. tenuis (Willd.) Schult. var. verrucosa (Svens.) Svens.] for central NE may be based upon misidentifications of E. compressa. Much of the E. compressa in our region has more slender, often angular culms suggestive of E. verrucosa. The species are otherwise separable on the basis of achene characters. E. verrucosa has olivaceous achenes with a cellular-reticulate pattern of depressions on the surface. This is in contrast to the golden to brown, warty or wrinkled achenes of E. compressa.

GIF- Distribution Map

Map key

Previous Section -- Eleocharis acicularis (L.) R. & S. -- Needle spikesedge
Return to Family -- Cyperaceae - The Sedge Family
Next Section -- Eleocharis erythropoda Steud. -- Spikerush

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