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

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THE BOLETES OF MICHIGAN

Observations.-The very slimy glabrous dark vinaceous-brown
pileus when young, the lack of a veil, pale yellow pores and white
unspotted stipe at first, distinguish this species. It is often collected for
food in pine plantations in the southern part of the state.
Material examined.-Chippewa: Shaffer 1948; Smith 43929.
Huron: Mazzer 5217. Luce: Smith 38489, 58015. Oakland: Smith 75171.
Washtenaw: Smith 66442, 67585.
24a. Suillus brevipes var. subgracilis Smith & Thiers
Contrib. toward a Monograph of N. Amer. Sp. of Suillus p. 99. 1964
Illus. P1. 29.
Pileus 3-8 cm broad, obtuse to convex, in age broadly convex,
glabrous, glutinous when wet, varnished when dry, pale pinkish tan when
young, dingy ochraceous in age or on the disc about "cinnamon-buff';
margin curved in at first and naked at all times; in age the pileus surface
appearing slightly virgate beneath the slime. Context white at first, slowly becoming pale lemon-yellow, olive-gray in FeS04, pinkish then vinaceous-drab in KOH, taste and odor not distinctive.
Tubes up to 1 cm deep, adnate to depressed around the stipe,
lemon-yellow, pores up to 1 mm broad when mature, bright yellow, not
staining either brownish or bluish when bruised.
Stipe 3-5 cm long, 7-12 mm at apex, solid equal or nearly so,
cortex lemon-yellow with the pith paler, surface white and lacking glandular dots, gradually becoming bright lemon-yellow or apex lemonchrome, some grayish brown discoloration of the surface fibrils occurs
lower down.
Spore deposit pale cinnamon; spores 6.5-9 X 2.4-3 u, smooth,
thin-walled, obscurely inequilateral in profile, in face view nearly oblong,
greenish hyaline in KOH, yellowish in Melzer's.
Basidia 16-20 X 4-5 i, 4-spored, hyaline in KOH, clavate. Pleurocystidia in fascicles with rusty brown to vinaceous-brown incrusting pigment around the base of the bundle, individual cystidia with brown to
vinaceous-brown content and either smooth or incrusted. Cheilocystidia
abundant, tube edge often heteromorphous, also incrusted with reddish
brown amorphous pigment, the details of the cystidia the same as for
the pleurocystidia. Caulocystidia in patches or fascicles, individual
cystidia 40-70 X 5-9 g, cylindric to clavate, with vinaceous-brown content in KOH, bases surrounded by some amorphous incrusting pigment.