This northern species is a close relative of hyalinolepis that may occur in Ky. but verification is needed. It was not mapped in Ky. by FNA 23 but it was reported by J from the Coastal Plain, perhaps based on misidentifications of hyalinolepis (as in some early colls. from JEFF by MM). C. lacustris has also been misidentified in Tenn. (Ch; D. Estes, pers. comm.).There may be reliable records from close to Ky. in Ill., Ind. and Ohio (K). C. lacustris differs as follows (FNA 23): longest ligules 13-56 mm (versus 2-12 mm), much longer than wide (versus < twice); culms lateral from rhizome (versus central), basal sheaths bladeless (versus with marcescent remains of leaves); perigynia usually strongly 14-28-veined (versus obscurely 10-15-veined). But FNA 23 stated: "Rare hybrids between Carex lacustris and C. hyalinolepis, C. pellita, C. trichocarpa... and C. utriculata are known; the hybrids are sterile and intermediate in morphology and can form extensive clones."