Juncus ensifolius Wikstr.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
Species Description - Rhizomatous; stem 2–6 dm, flattened; lvs mostly crowded below, the larger ones 10–40 cm × 1.5–6 mm, all equitant; blade with scattered, irregular, partial or complete partitions; heads few, many-fld, 1+ cm thick, mostly dark; fls axillary to evident, hyaline-scarious bracts but not prophyllate; outer tep 2.5–4 mm, acuminate, inner a little shorter and often a little wider and less pointed; stamens 3 (in ours); fr incompletely 3-locular; seeds 0.4–0.6 mm, apiculate at both ends; 2n=20. Wet places; widespread in the w. cordillera, disjunct in Ashland Co., Wis., Mich., and along the Delaware R. in N.Y. Ours is var. ensifolius.