281b. Carex laxiculmis Schweinitz var. copulata (L. H. Bailey) Fernald, Rhodora. 8: 183. 1906.
Carex digitalis Willdenow var. copulata L. H. Bailey, Mem. Torrey Bot. Club 1: 47. 1889; C. ×copulata (L. H. Bailey) Mackenzie
Leaves usually bright green; widest blade 5.3–8.3 mm wide. Longest staminate spike 6–20(–23) mm.
Fruiting spring–early summer. Low, wet, deciduous or mixed deciduous-evergreen forests, mesic slopes to along edges of springs, seeps, and streams, usually clay soils; 0–1000 m; Ont.; Ala., Ark., Ill., Ind., Iowa, Ky., Mich., Mo., N.C., Ohio, Tenn., Va., W.Va., Wis.
Carex laxiculmis var. copulata has been treated as a variety of C. digitalis or C. laxiculmis, as a distinct species, and as a hybrid between C. digitalis and C. laxiculmis. Regular pairing during metaphase-I indicates that C. laxiculmis var. copulata is not a by-product of hybridization (R. F. C. Naczi 1999). In lateral spikes, a proximal sterile scale or scale subtending a staminate flower clearly places the affinity of this variety with C. laxiculmis rather than C. digitalis (C. T. Bryson 1980).