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

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THE BOLETES OF MICHIGAN

naked to minutely appressed-fibrillose; cutis in age often separating to
form minute areolae. Context whitish when young but soon pale yellow,
soft, unchanging, with a watery green line above the tubes, odor mild to
slightly fragrant, taste of pellicle mild to acid, with FeS04 olive-gray;
KOH on cutis olive-gray, on context "Natal-brown" (vinaceous-brown).
Tubes adnate-subdecurrent, about 1 cm deep, pallid at first, but
pores small and pale yellow becoming dingy yellow when mature, not
staining when bruised, when young a boletinoid configuration more or
less evident, in age up to 1 mm broad and somewhat spotted from colored
fascicles of cheilocystidia, staining dingy cinnamon in age when bruised,
when very young often scantily beaded with droplets of a cloudy liquid.
Stipe 4-8 cm long, 1-2 (2.5) cm thick at apex, equal or narrowed
to a point at the base, solid, white inside at first, but soon bright yellow
in apical region, tinged cinnamon toward the base, surface whitish but
soon bright yellow above, pallid downward but base becoming dingy
cinnamon, covered overall by pinkish tan to vinaceous-brown glandular
dots; veil none.
Spore deposit dingy cinnamon; spores 7-9 (10) X 2.5-3.5 t,
smooth, yellowish in KOH and Melzer's, oblong or tapered slightly to
apex, in profile somewhat inequilateral.
Basidia 4-spored, 18-23 X 5-6 A, clavate, hyaline in KOH, merely
yellowish in Melzer's. Pleurocystidia in bundles with brown incrusted
material around the base, individual cystidia 36-50 X 7-9 Au, clavate to
subcylindric, hyaline or with yellowish to brown content. Cheilocystidia
similar to pleurocystidia. Caulocystidia 40-70 X 7-10 L, clavate, subfusiform to cylindric, mostly with colored content, bases of clusters surrounded by brown pigment, content of cystidia hyaline to colored and
mostly coagulated; incrusting pigment present over much of the caulohymenium.
Tube trama of gelatinous divergent hyphae from a colored floccose
central strand. Epicutis of pileus a gelatinous trichodermium of hyphae
4-7 A. broad, collapsing to form a pellicle in KOH, the content dingy
ochraceous to bister, some incrusting material present in the layer.
Clamp connections absent.
Habit, habitat, and distribution.-Scattered, gregarious or cespitose
under various species of pine but abundant under white pines, especially
in plantations. It fruits during the summer and fall and is one of the
most common species in the state.
Observations.-This is one of the best species of Suillus for the
table and the one most frequently collected. It is not as slimy as the
Slippery Jack. The color pattern of the pileus is from white in buttons