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

108

THE BOLETES OF MICHIGAN

the stipe generally and that it does not change color in a characteristic
pattern as it ages. For this reason we exclude it from Leccinum and
agree with Singer that it is a Tylopilus.
47. Tylopilus alboater (Schweinitz) Murrill
Mycologia 1:16. 1822
Boletus alboater Schweinitz, Schr. Naturf. Ges. Leipzig 1:195. 1822.
Suillus alboater (Schweinitz) Kuntze, Rev. Gen. P1. 3(2):535. 1898.
Porphyrellus alboater (Schweinitz) Gilbert, Bolets, p. 99. 1931.
Pileus (3) 4-8 (15) cm broad, convex becoming plane or remaining
broadly convex; surface dry, appearing minutely granular under a lens,
glabrous but with a hoary bloom at first, color evenly "dusky drab"
(dark gray) overall, margin extended slightly beyond the tubes but not
forming a conspicuous sterile band. Context thick and firm, pale grayish
white, soon changing to near "cinnamon-drab" (vinaceous-gray) or more
reddish and finally blackish, odor and taste not distinctive.
Tubes 5-8 (10) mm deep, pallid ("tilleul-buff'), soon flesh color,
slightly adnate at first, finally deeply depressed; pores white at first,
soon "pale vinaceous-fawn" and staining black where bruised, about 2
per mm.
Stipe 4-10 cm long, 2-4 cm thick, clavate becoming equal, solid,
flesh pale grayish and changing to reddish and then black when bruised,
black in the base when collected, surface concolorous with pileus or
apex paler, reticulate at apex or unpolished overall (surface similar to
that of pileus).
Spore deposit vinaceous; spores 7-11 X 3.5-5 g, smooth, wall
scarcely thickened, narrowly ovate in face view, somewhat inequilateral
in profile, nearly hyaline in KOH, pale dingy yellow-brown to dull rusty
brown in Melzer's.
Basidia 16-20 X 7-8 iu, 4-spored, short and fat, yellowish to pale
brownish in KOH, scarcely darker in Melzer's. Pleurocystidia 36-50 X
10-16 u, fusoid-ventricose, thin-walled, smooth, content pale bister in
KOH, darker bister in Melzer's. Caulocystidia 32-48 X 9-14 L, clavate,
mucronate or somewhat fusoid-ventricose, walls smooth and thin, content pale to dark bister in KOH and homogeneous.
Tube trama of the Boletus subtype, many of the hyphae with dark
granules in KOH or in Melzer's but nonamyloid. Pileus cutis an intricately interwoven layer of hyphae 4-7 g wide having short and long, tubular
cells, the end-cells tubular to narrowed slightly to the apex, walls thin
and smooth, content in KOH dark smoky ochraceous, in Melzer's the