Plants without conspicuous rhizomes. Culms 20-80 cm, 0.8-1.5 mm wide basally, 0.4-0.5 mm wide distally. Leaves: sheaths tight, green, fronts hyaline; ligules less than 2, wider than long; widest leaf blades 1.3-1.9 mm wide. Inflorescences with 4-8 spikes, 3-7 cm × 5-7.5 mm; proximal internodes more than 2 times as long as proximal spikes; proximal bracts to 5(-10) cm; spikes with 3-8 spreading or reflexed perigynia. Pistillate scales hyaline with green midvein, ovate, 1.4-2.3 × 0.9-1.6 mm, body 1/2 length of perigynium, apex obtuse, acute, or awned. Anthers 0.8-1.3 mm. Perigynia green, faces not veined, 2.6-3.8 × 1-1.5 mm, base of body spongy, thickened, longitudinally striate adaxially, spongy region 1-1.5 mm, margins serrulate distally; beak 0.4-1 mm, apical teeth 0.1-0.2 mm. Stigmas straight or slightly twisted, 0.03-0.06 mm wide. Achenes ovate to obovate, 1.5-2 × 1-1.4 mm. 2n = 58. Fruiting mid-late spring. Mesic to wet-mesic deciduous and mixed forests, often seasonally wet areas; 50-1000 m; Man., N.B., N.S., Ont., Que.; Ala., Ark., Conn., Del., D.C., Ill., Ind., Iowa, Kans., Ky., La., Maine, Md., Mass., Mich., Minn., Miss., Mo., Nebr., N.H., N.J., N.Y., N.C., N.Dak., Ohio, Okla., Pa., S.C., S.Dak., Tenn., Vt., Va., W.Va., Wis. The name Carex rosea has frequently been misapplied to C. radiata.
From Flora of Indiana (1940) by Charles C. Deam
Very common in both dry and moist woods. This species and C. convoluta are perhaps the most plentiful woodland sedges in the state as a whole.
Small Cespitose; stems 2-8 dm, erect, slender, the fertile ones 0.8-1.5 mm thick at base; lvs elongate, the widest ones 1.3-1.9 mm wide; spikes 4-7, androgynous, sessile, closely aggregated or the lower often distinctly separate; bracts setaceous, the lowest often surpassing the infl; pistillate scales persistent, shorter than the perigynia, rounded to acute, seldom short-awned; perigynia 3-20, light green, widely spreading or reflexed at maturity, planoconvex, lance-ovate, 2.6-3.8 mm, two-fifths as wide, spongy and somewhat swollen at the subtruncate or broadly rounded base, nerveless, or obscurely nerved near the base, gradually tapering or slightly acuminate into a serrulate, very shortly bidentate beak scarcely a third as long as the body; achene lenticular, ovate to obovate, 1.5-2 mm, occupying the upper half of the body of the perigynium, its base 0.5-0.9 mm above the base of the perigynium; stigmas very slender, straight to slightly twisted, only 0.03-0.06 mm wide; 2n=58. Moist woods and edges of ponds, requiring more moisture than the next 2 spp.; N.S. and s. Que. to Man. and N.D., s. to N.C., Ala., and Mo. (C. rosea, misapplied) The 2 following spp. are closely allied to C. radiata. The characters are confluent, but the populations apparently not.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.