Laharpe Densely cespitose; stems rather soft, to 1 m, rather coarsely ridged-sulcate with 10-20 ridges, the epidermal cells over the ridges enlarged; basal sheaths to 2 dm, bladeless, mostly dark reddish-brown or blackish; invol lf 10-20 cm, appearing like a continuation of the stem; infl apparently lateral, many-fld, open to fairly compact, mostly 1.5-6+ cm wide; fls prophyllate; tep 2.5-3.5 mm, pale brown, rigid, lanceolate, long-acuminate, ±closely investing the fr, the outer a little longer than the inner and often loose or slightly spreading at the tip; anthers 3; fr trilocular, shorter than to about equaling the tep, broadly obtuse or rounded to truncate or retuse at the tip, usually not mucronate; 2n=40. Wet, boggy or sandy, rather low-nutrient soils; Nf. to Minn. and sw. Mont., s. to N.C. and Ind. (J. effusus var. p.)
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.