Northern Prairie Wildlife Research Center


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Aquatic and Wetland Vascular Plants of the Northern Great Plains

62. Cyperaceae, the Sedge Family

10. Rhynchospora Vahl -- Beak-rush

1. Rhynchospora capillacea Torr.

Small, tufted, grasslike perennial; culms capillary, 0.5-4 dm tall; leaves filiform, involute, 0.2-0.4 mm wide. Inflorescence of 1 or 2 small, ovoid to oblong clusters of spikelets, sometimes only 1 terminal spikelet present, otherwise the terminal cluster containing 2-10 spikelets; lateral cluster, when present, containing 1-4 spikelets, remote from the terminal cluster, subsessile or short-peduncled, each cluster subtended by 1-few short, setaceous bracts. Spikelets ovoid to ellipsoid, 3-7 mm long; scales spirally imbricate, brown, elliptic or elliptic-ovate, the pale midvein prolonged into a cuspidate tip, the lower scales empty, the terminal ones mostly staminate, only 1-2(5) achenes produced from perfect-flowered scales in the middle portion of each spikelet; perianth bristles 6, retrorsely barbellate, exceeding the achene, sometimes some additional shorter bristles present; stamens 3; styles 2. Achenes obovate-oblong, biconvex, the body tawny, semiglossy, 1.7-2.1 mm long, truncate above at the juncture with the beak, narrowed below to a stipitate base; beak dull brown, narrowly triangular, 0.7-1.1 mm long. Jul--Aug. Calcareous fens and bogs; rare and scattered in ND and SD; (Newf. to Alta., s to VA, TN, OH, IN, MO and SD).
GIF- Distribution Map

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