The boletes of Michigan, by Alexander H. Smith and Harry D. Thiers.

TYLOPILUS 125
he described for the context of T. tabacinus. This, and his variable spore
size (8.8-17 p long), could easily indicate a different species. His measurements of the cystidia are clearly too small for T. tabacinus (18-45 X
4.5-8.5 i-). We found no significant hyphal incrustations in the type of
T. tabacinus. The only thick-walled hyphal elements we found on the
type belonged to a member of the Fungi Imperfecti which had invaded
the dermal zones. The walls of its hyphae varied from hyaline near the
tip to dark brown and thick farther back, and conidiophores projected
in a manner sometimes resembling setae.