Cheilocystidia are the most distinctive character of the species, and they separate it at once from M. epipterygiodes. There are also differences in the colors and the manner in which they change, but in view of the great variation of yellow, green, and gray in this group, I hesitate to emphase them. One of two specimens of M. viscosa sent to me by Dr. Rolf Singer has cheilocystidia like those of M. griseoviridis; the other, like those of Mycena epipterygia. In the American collections this difference has been found constant, and serves to distinguish readily both M. griseoviridis and M. epipterygia. On the basis of Singer’s specimen, Mycena griseoviridis may be said to occur in Europe also. Kauffman’s M. epipterygiodes variety A also belongs here, but his specimens blackened in drying and now are not typical in their appearance.
This species was placed in Section Viscosae by A.H. Smith.