Plants colonial, long-rhizomatous. Culms (0.8-)14-75 cm, smooth distally. Leaves: proximal sheaths with blades, pale brown, 3-6 mm thick; ligules 0.4-3.5(-8.5) mm, usually wider than long; leaf blades somewhat glaucous, flat, 5.5-33 cm × 1.4-4.7 mm, folded at bases, margins revolute, herbaceous. Inflorescences 3.2-21 cm, 1.7-3.5(-4.3) times as long as proximal bract; proximal bract (1.3-)2-9 cm, sheath 0.5-2.4 cm, blade 1.1-7.1 cm; pistillate spikes densely flowered, ovoid to cylindric, 0.8-2.9 cm × 4.5-7.5 mm; lateral spikes erect or ascending on stiff peduncles. Pistillate scales dark reddish purple with hyaline margins, green centers, apex obtuse, centers papillose. Perigynia ascending to spreading, yellowish green to brown, often suffused with reddish purple, broadly obovoid, 2.6-5.1 × 1.4-2.4 mm; beak minute, sharply bent. Achenes pale brown, 1.8-2.9 × 1.3-1.9 mm. 2n = 32. Fruiting late spring-early summer. Wet to dry, usually sandy, acidic fields; 0-20 m; Greenland; St. Pierre and Miquelon; N.B., Nfld. and Labr., N.S.; Conn., Maine, Mass., N.H., N.Y., R.I.; Eurasia. Carex panicea is introduced into continental North America and native to Greenland; however, some people believe that the taxon was introduced to the New World by the Vikings.
Much like no. 109 [Carex livida (Wahlenb.) Willd.]; somewhat bluish-green, but scarcely glaucous; main lvs 2-5 mm wide, flat, shorter than the stems; sheaths conspicuous, the lowest 1-2 cm; terminal spike 1.5-3 cm, long- pedunculate; lateral spikes generally well separated, the lower long-pedunculate (but not basal), the upper less so or subsessile; pistillate scales ovate, shorter than but about as wide as the perigynia, these stoutly fusiform to obovoid, obscurely trigonous, ribbed on the lateral angles, beakless or minutely beaked; achene nearly filling the perigynium; 2n=32. Native of Europe, intr. in fields, lawns, and meadows from N.S. and N.B. to N.J.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.