Plants not cespitose; short-rhizomatous. Culms 10-40 cm, triangular, scabrous distally Leaves plane, 1.5-3 mm wide, equaling culms. Spike with staminate portion separated from pistillate portion by short but conspicuous internode, with pistillate portion 0-2 branched, 5-23 × 1.3-2.3 mm. Pistillate scales green, proximal foliaceous, long-awned. Staminate scales green to pale brown, apex obtuse to acute. Anthers 1.9-3 mm. Perigynia 1-5, light green to brownish green, with 2 strong marginal veins, otherwise veinless, 5-6 × 2.5-3 mm.

Fruiting late May-late Jun. Dry, open or partly shaded, rocky canyon slopes; of conservation concern; 1000-1700 m; Calif.

Carex tompkinsii is known to occur only in Fresno County, California. Specific status may not be warranted for this taxon; until a thorough review of its taxonomy has been completed, it seems best to maintain its rank to bring it to the attention of field botanists.