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

TYLOPIL US

109

same layer having a homogeneous to granular content slightly paler than
in KOH mounts, the colored layer forming an epicutis 4-6 hyphae deep,
but beneath this is a thick layer of hyphae similar anatomically but not
as highly colored in either medium. Context hyphae adjacent to the
cutis sometimes with orange-brown homogeneous content in Melzer's.
Clamp connections absent.
Habit, habitat, and distribution.-Solitary to scattered in hardwood
forests especially along roads, late summer, not recorded for certain in
Michigan.
Observations.-The only specimen we have located among Kauffman's collections is misidentified. Hence we cannot claim for certain
that the species occurs here. It is to be expected in our southern tier of
counties, however, so a description is included based on fresh material
(Smith 73072) collected in Maryland. The darkening of the flesh is
much like that observed in many species of Leccinum and it is curious
that in that genus certain species have a spore-deposit color not too
different from that observed in some species of Tylopilus.
No thick-walled elements were found on the pileus or stipe (see
Singer, 1947). It is likely that we have here a cluster of variants needing
further study. We have not attempted this since the species and its
variants are, to say the least, rare in our area, and such a study should
be based on fresh material.
Stirps FELLEUS
KEY
1. Pileus whitish and surface wrinkled like parchment......... T. intermedius
1. Pileus not as above.................................. 2
2. Pileus and stipe violaceous when young; stipe mostly only slightly
reticulate at the apex.................... T. plumbeoviolaceus
2. Pileus pale to dark tan to dull cinnamon.................. 3
3. Pleurocystidia with a large hyaline globule as seen in KOH mounts; habitat
under pine or spruce on swampy or barren sandy soil... T. felleus var. uliginosus
3. Pleurocystidia lacking a central globule; often growing around old conifer
stumps but terrestrial as well.................. T. felleus var. felleus
48. Tylopilus intermedius Smith & Thiers, sp. nov.
Illus. PI. 51.
Pileus 6-12 (15) cm latus, late convexus demum subplanus, siccus,
subrugulosus, albidus, tactu tarde brunneus, amarus; tubuli albidi,