Aquatic and Wetland Vascular Plants of the Northern Great Plains
61. Juncaceae, the Rush Family
1. Juncus L. -- Rush7. Juncus compressus Jacq.
Perennial from dark brown to black rhizomes, 2-6 dm tall. Leaves cauline as well as basal, some arising near or within the upper 1/2 of the stem; blades flat, to 2 dm long, 1-2 mm wide; sheaths green with broad membranous margins, rounded and entire or cleft into 2 low, rounded auricles at the summit. Inflorescence oblong, many-flowered, 2-8 cm long, the branches erect to ascending; involucral leaf seldom surpassing the inflorescence; bracteoles mostly obtuse to rounded, ca. 1 mm long. Flowers solitary, mostly on short pedicels, dark brown, 2-3 mm long; tepals blunt and incurved at the tip, the outer ones slightly longer than the inner, the inner ones with a scarious margin toward the tip; stamens 6, reaching the middle of the perianth, the anthers ca. 1 mm or less long, scarcely longer than the filaments. Capsules obovoid, 1-locular, much surpassing the perianth; seeds obliquely cylindric-pyriform, brown, 0.5-0.6 mm long. Jun--Aug. Apparently intro. to N.Amer. from Europe where it is widespread, adventive here from e and s Can.; rare, with records from along the Missouri R. in Emmons, Burleigh and Williams Counties in ND, also ne WY, probably on the increase; (Newf. to N.S. and Que. and w to Man., ND and MT; also Eurasia).
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