Aquatic and Wetland Vascular Plants of the Northern Great Plains
62. Cyperaceae, the Sedge Family
11. Scirpus L. -- Bulrush8. Scirpus pallidus (Britt.) Fern. -- Pale bulrush
Loosely tufted perennial with short rhizomes, 5-17 dm tall, the culms trigonous. Leaves sheathing most of the culm; blades ascending, usually not surpassing the inflorescence, 5-17 mm wide; sheaths entirely green; involucral bracts 3-4, foliaceous, slightly to much exceeding the inflorescence, the longest to 15 cm long. Inflorescence a terminal, rather compact, umbelliform cyme containing many dense glomerules of numerous spikelets, the glomerules densely clustered at the ends of pedicels to 12 cm long; spikelets very numerous and crowded, 2-5 mm long, 1-2.5 mm thick; scales hyaline except for the broad, green midvein, blackish on the sides, mostly 2-2.5 mm long including an awn 0.4 mm or more long; perianth mostly of 6 white to tan bristles shorter than or equaling the achene; stamens 3; styles trifid. Achenes light green to pale tan, unequally trigonous, the ventral side broadest, the achene body 0.7-1 mm long, 0.5-0.7 mm wide, with a beak to 0.2 mm long. Jul--Aug. Wet meadows, shores, ditches, stream banks, springs and other wet places; common e and c, less so w; (Ont. to Alta. and WA, s to MO, TX, NM and AZ). S. atrovirens Willd. var. pallidus Britt.
Rarely entering the region in the extreme ne part (e.g., Pembina Co., ND) is the very similar S. atrovirens, of which S. pallidus is often treated as a variety. S. atrovirens differs from S. pallidus chiefly as follows: Scales dark green on the sides, eventually turning brownish or blackish, 1-2 mm long including a mucro 0.1-0.2 mm long.
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