Aquatic and Wetland Vascular Plants of the Northern Great Plains
62. Cyperaceae, the Sedge Family
11. Scirpus L. -- Bulrush11. Scirpus saximontanus Fern.
Small, tufted annual 1.5-4 dm tall; culms several to many, terete or essentially so, grooved when dried. Leaves 1 per culm, mainly basal, sheathing only or with a short blade mostly less than 1(-4) cm long; principal involucral bract prominent, erect, resembling a continuation of the culm, 3-15 cm long; other involucral bracts none or weakly developed, shorter than to surpassing the inflorescence, projecting laterally below the spikelets. Inflorescence appearing lateral, comprised of 3-8 spikelets, all essentially sessile or some in clusters of 2-3 at the tips of short pedicels to 1 cm long; spikelets ovoid to oblong-cylindric, 4-13 mm long, 2.5-3 mm thick; scales whitish to eventually dull yellowish-brown, with a prominent green midrib, scarious-margined, rotund-ovate, strongly convex dorsally, 2.5-3 mm long, mucronate or the lower scales with an awn to 1 mm long; perianth bristles absent or otherwise variable; stamens 3, the straplike filaments often adherent to the achene; styles trifid. Achenes light green to eventually dark brown, strongly trigonous, obovoid, 1.4-1.8 mm long, conspicuously cross-ridged on the surface, short-beaked. Aug--Sep. Muddy shores and flats where previously flooded; occasional in SD and NE; (IA and SD, s to MO, TX and into n Mex.). S. supinus L. var. saximontanus (Fern.) Koyama.
Reports of S. hallii A. Gray and S. smithii A. Gray in the
region are very likely based on the above. Both are similar to S. saximontanus
but have bifid styles and lenticular (plano-convex rather than strongly trigonous)
achenes. S. hallii has the achenes cross-ridged like those of S.
saximontanus, whereas the achenes of S. smithii are smooth.
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