Plants densely cespitose. Culms 50-90 cm; vegetative culms with numerous leaves spaced evenly along distal 1/2. Leaves: sheaths adaxially green-veined nearly to collar with V-shaped hyaline band extending 4-20 mm proximal to collar, somewhat loose, expanded near summit, ± wing-angled, adaxially firm, summits thin, U-shaped to rounded, sometimes shortly prolonged beyond collar; distal ligules 4-9 mm; blades 3-6 per fertile culm, 18-40 cm × 3-7 mm. Inflorescences nodding, open at least proximally, pale brown, 2.5-6 cm × 7-14 mm; proximal internode 5-12(-18) mm; 2d internode 3-11 mm; proximal bracts scalelike, sometimes bristlelike to 3 cm. Spikes 8-15, proximal spikes well spearated, nearly globose, 9-12 × 6-8(-9) mm, base tapered, apex rounded. Pistillate scales white to brown with brown or green midstripe not reaching tip, oblong-lanceolate to oblong-ovate, 2-2.7 × 0.9-1.5 mm, shorter and narrower than perigynia, apex obtuse to nearly acute. Perigynia usually 15-30 per spike, ascending to reflexed, with divergent beak, pale brown; conspicuously (3-)5-8-veined abaxially, conspicuously 3-6-veined adaxially, lanceolate, flat to plano-convex, thin, 2.9-4.3 × 1.2-1.6 mm, 0.3 mm thick, margin flat, including wing 0.2 mm wide; beak sometimes red-brown at tip, flat, ciliate-serrulate, distance from beak tip to achene 1.6-2.4 mm. Achenes ovate to oblong, 1.1-1.7 × 0.6-1 mm, 0.3 mm thick. 2n = 64.
In many respects Carex projecta is intermediate between C. cristatella and C. tribuloides; it is sometimes difficult to distinguish from those species. However, when all three species occur together, C. projecta flowers and fruits first, C. tribuloides later, and C. cristatella latest of all. When C. projecta is in mature fruit, C. cristatella will be just past flowering.
Much like no. 71 [Carex tribuloides Wahlenb.]; spikes subglobose to obovoid, 5-8 mm, about as thick, distinct and ±separated (at least the lower) in a rather lax and flexuous infl 3-5 cm; perigynia mostly 15-30, loosely ascending-spreading at maturity, dull brown, 3-5 mm, the wing usually gradually narrowed from the middle to the base, sharply nerved dorsally, obscurely so ventrally; 2n=64. Open swamps and wet meadows; Nf. to Man., s. to W.Va., Ill., and Mo. (C. tribuloides var. reducta)
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.