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.
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.