This widespread western and northern species of diverse habitats probably occurs in Ky., but documentation is inadequate, and there has been confusion in nomenclature with frondosa. M. mexicana is reported from close to northern and eastern borders of the state (FNA 25, K, W). There is a herbarium sheet that has verified mexicana collected by C.W. Short (KY), but with two labels; (1) "alluvium of the Ohio", Ky. 1840; (2) "rocky woods... map" (initially determined as Agrostis lateriflorus). Also, plants that may be this species have been recently found along wooded streamheads in LAUR (JC for KY), but flowering has not yet been observed.