Northern Prairie Wildlife Research Center
Aquatic and Wetland Vascular Plants of the Northern Great Plains
62. Cyperaceae, the Sedge Family
11. Scirpus L. -- Bulrush
10. Scirpus pungens Vahl -- Three-square
Slender rhizomatous perennial 2-10(14) dm tall; culms erect to gently
curved, trigonous, the sides concave to slightly convex. Leaves few,
mostly 1-3 per culm, sheathing the base of the culm, the blades typically folded
or channeled above, 1-2 mm wide (2-4 mm wide when flat), usually diverging from
the culm well within the lower 1/3 of its length and not overtopping it; principal
involucral bract erect, resembling a continuation of the culm, 2-8(18) cm
long; additional involucral bracts 1-2, appearing as enlarged sterile
scales subtending the spikelets. Inflorescence appearing lateral, comprised
of 1-4(6) sessile spikelets, these 5-20 mm long, 3-5 mm thick; scales
light to dark brown or reddish-brown, 3-5 mm long, mostly aristate and bifid,
the awn 0.5-2 mm long; perianth of 1-6 bristles, variable in length,
shorter than the achene; stamens 3 or sometimes 2, the straplike filaments
often remaining attached at the base of the achene; styles trifid or
bifid. Achenes light green or tan to dark brown, trigonous or lenticular,
ventrally flat, the body 2-3 mm long, the beak prominent, 0.3-0.5 mm long. Jun--Sep.
Shores, stream banks, wet meadows, ditches, seepage areas and other wet places;
common, often abundant; (S Can., s to S.Amer.; also Europe, Australia and New
Zealand). S. americanus Pers., misapplied.
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