Carex tonsa var. rugosperma has long been known as C. rugosperma but C. tonsa has priority. The two varieties of C. tonsa may occur together; intermediates are found occasionally. Plants with virtually glabrous perigynia may have long, scabrous leaves. Plants with a pubescent perigynia apparently never have coriaceous, short, and nearly smooth leaves.
From Flora of Indiana (1940) by Charles C. Deam
Infrequent in the northern tier of counties. It is found in dry, sandy oak woods, open drained low woods, and on borders of drained marshes.