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

TYLOPIL US

111

Observations.-Bruised spots on the pileus slowly stain brown, a
feature of T. peralbidus, but our species never has the colors of the
pileus given by Singer for T. peralbidus, the spores are larger, and the
pileus is wrinkled like parchment. T. intermedius is also close to T.
rhoadsiae, but is readily distinct by having only faint reticulation over
the apex of the stipe in contrast to being strongly reticulate, and again
the wrinkled pileus is an added difference. Singer lists T. rhoadsiae as
extending as far north as Michigan, but we have seen no material which
fits the description. Murrill (Ic) described the stipe as beautifully
reticulate and Singer's account bears this out, although he apparently
accepts Snell's B. felleus f. albiceps as a Michigan record. However, the
basidiocarps of the latter in the part of Kauffman's collection preserved
at Michigan do not have any sign of a reticulum on the stipe and in this
respect differ sharply from T. felleus f. felleus. We regard T. rhoadsiae as
southern in distribution and not yet known in the central Great Lakes
area, and T. intermedius as an autonomous species endemic to this
region.
Material examined.-Oakland: Smith 64301. Washtenaw: Hoseney
585, 630; Kauffman, type of B. felleus f. albiceps; Smith 64186, 6450.
49. Tylopilus plumbeoviolaceus (Snell & Dick) Singer
Amer. Midl. Nat. 37:93. 1947
Boletus plumbeoviolaceus Snell & Dick, Mycologia 33:32. 1941.
Illus. P1. 52.
Pileus 4-15 cm broad, convex at first, becoming broadly convex to
nearly plane at maturity, margin slightly inrolled at first; surface dry and
unpolished, occasionally becoming rimulose in age; color at first distinctly violaceous, becoming darker slate in the young pilei and then changing to browner at maturity (from "heliotrope-gray" through "dark vinaceous-drab" to near "drab" at maturity), or finally dingy cinnamon.
Context firm, white, only slightly if at all discoloring, taste very bitter,
odor slight, not distinctive.
Tubes 1-2 cm deep, depressed around the stipe, cream colored at
first, near pale vinaceous-tan at maturity, pores small and nearly round
at first, 1-2 per mm, broader and slightly irregular at maturity.
Stipe 8-12 cm long, 10-17 mm thick at the apex, somewhat swollen
centrally at first, becoming equal, at times slightly and evenly enlarged
downward at maturity; surface glabrous and only with a faint reticulation at the apex or not reticulate; color at first a mottled dark viola