Northern Prairie Wildlife Research Center
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.
Previous Section -- Eleocharis acicularis (L.)
R. & S. -- Needle spikesedge
Return to Family -- Cyperaceae - The
Next Section -- Eleocharis erythropoda Steud.