Plants without conspicuous rhizomes. Culms 10-80 cm, 1-2.4 mm wide basally, 0.5-1 mm wide distally. Leaves: sheaths tight, green or, sometimes, green-and-white-mottled, fronts hyaline; ligules to 2 mm, usually longer than wide; widest leaf blades 1.1-3(-4) mm wide. Inflorescences forming dense heads, with 3-8 spikes, 0.7-2 cm × 4.5-9 mm; proximal bracts to 2 cm; spikes with 6-10 ascending or spreading perigynia. Pistillate scales hyaline with green midvein, ovate, 1.5-2.5 × 0.9-1.2 mm, not more than 1/2 length of perigynia, apex acute to cuspidate. Anthers 0.6-1.7 mm. Perigynia pale green, veinless or weakly veined abaxially, 2.5-3.5 × 1.5-2.1 mm, body ovate, widest at 0.25-0.4 length of body, margins smooth or serrulate distally; beak 0.3-0.8 mm, apical teeth 0.1-0.3 mm. Achenes circular, 1-1.5 × 1-1.5 mm. Fruiting late spring. Dry grasslands, roadsides, open forests, forest edges, lawns; 100-300 m.; Ont.; Ala., Ark., Calif., D.C., Fla., Ga., Ill., Ind., Iowa, Kans., Ky., La., Md., Mich., Miss., Mo., Nebr., N.J., N.Y., N.C., Ohio, Okla., Pa., S.C., Tenn., Tex., Va., W.Va., Wis. Carex leavenworthii is introduced in California and Wisconsin. Carex leavenworthii is easily confused with C. cephalophora and consequently may be overlooked.
From Flora of Indiana (1940) by Charles C. Deam
Frequent, except in the lake area, in open grassy, generally dry or sandy, oak woods and bordering thickets; occasionally bordering woods in clay fallow fields.
Densely cespitose, the stems 2-5 dm, conspicuously exceeding the lvs, or the lvs more elongate in moist ground or shade; lvs 1-3 mm wide; infl, spikes, and pistillate scales as in the typical var. of no. 19 [Carex cephalophora Willd]; perigynia greenish-stramineous, spreading, broadly ovate, planoconvex, 2.5-3.3 mm, three-fifths to three-fourths as wide above the broadly rounded, truncate, or even subcordate base, inconspicuously rough-margined or smooth distally, the sharply bidentate beak a fourth as long as the body. Dry open ground or dry woods; N.Y. and N.J. to Fla. and Tex., thence n. to Io., s. Mich., and sw. Ont.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.