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

SUILL US

65

dular dots which become dark brown in age, in age with vinaceous stains
over basal part where handled.
Spores 6-7.5 X 2.8-3.2 g, pale yellow in KOH, smooth, oblong in
face view, suboblong in profile. Basidia 4-spored. Pleurocystidia in fascicles, 34-50 X 6-9 p, subcylindric to narrowly clavate, with incrustations
around the bundle dark brown and the cystidia with content similarly
colored as revived in KOH. Cuticle of pileus a thick layer of interwoven
gelatinous hyphae 2-5 ju wide. No clamp connections observed.
Habit, habitat, and distribution.-Under jack pine (P. banksiana)
Yellow Dog River pine barrens, Marquette County, June 25, 1968, N. J.
Smith 1052.
Observations.-This species has the stipe almost as conspicuously
dotted as S. placidus and hence cannot justifiably be classed with S.
albidipes. Like other western species, however, it appears to be rare in
the state. It should also be pointed out that the spore size is at the
lower end of the range for typical S. glandulosipes.
23. Suillus placidus (Bonorden) Singer
Farlowia 2:42. 1945
Boletus placidus Bonorden, Mohl's Bot. Zeitung. 1I:204. 1861.
Ixocomus placidus (Bonorden) Gilbert, Bolets p. 132. 1931.
Illus. Pls. 26-27.
Pileus 3-10 cm broad, broadly convex when young, remaining so,
or becoming plane or finally with a wavy margin, margin naked; surface
glabrous and viscid to slimy, often appearing varnished if weather is dry,
soft to the touch, white to ivory-white at first, gradually becoming
yellowish, finally pale lemon-yellow, dingy olive with age when watersoaked, slime often becoming grayish to blackish with age, surface often
showing depressions as the soft context collapses. Context white but
slowly lutescent, when cut often slowly becoming pale vinaceous, taste
mild, odor mild to acidulous, with KOH dingy vinaceous, with ammonia
red.
Tubes 3-8 mm deep (rather shallow), at first adnate to depressed
around the stipe but soon decurrent, yellowish pallid when young, becoming yellow, unchanging when injured; pores pale yellow becoming
yellow, small (1-2 per mm), often beaded with pinkish droplets of an
exudate when young and fresh, often glandular dotted.
Stipe 4-12 cm long, (3) 5-12 (22) mm thick, equal, solid, becoming hollow, white within but soon lemon-yellow, surface white with