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

BOLETUS

305

slightly bitter, odor not distinctive, NH4OH on cuticle of pileus giving
no color change; cut context finally greenish gray.
Tubes about 1-2 cm deep, adnate to subdecurrent becoming depressed, pallid when very young but soon pale yellow and finally olivaceous-yellow; pores small to medium (1-2 per mm), round, becoming
somewhat angular, staining blue to greenish blue and then brownish
where injured.
Stipe 5-12 cm long, 8-30 mm thick at apex, enlarged downward,
finally nearly equal, solid, white within, reddish around wormholes, surface dry, smooth to slightly reticulated near apex, white when young,
often yellow ("Chalcedony-yellow") at the apex, white mycelium at the
base, finally becoming streaked brownish gray downward, often with
reddish flushes, especially toward the base.
Spore deposit near "Saccardo's olive" and "brownish olive"
(Singer), dingy olive-brown (Smith). Spores 9-15.4 X 3-4.5 /, narrowly
ovoid to subfusoid in a face view, in profile inequilateral, smooth, with
a hyaline sheath, greenish hyaline in KOH, yellowish to pale tawny in
Melzer's.
Basidia 4-spored, 20-26 X 9-10 g, yellowish in KOH and Melzer's.
Pleurocystidia 35-44 X 8-13 pu, fusoid-ventricose with a subacute apex,
hyaline to yellow in KOH, thin-walled, smootH. Cheilocystidia more or
less similar to pleurocystidia but many clavate cells also present.
Tube trama gelatinous and divergent, nonamyloid. Pileus cuticle
a tangled turf about 300, deep of hyphae 4-8 j in diameter, the
terminal cells tubular and obtuse, hyaline in KOH, thin-walled, nonamyloid. Clamp connections absent.
Habit, habitat, and distribution.-Solitary to gregarious or cespitose
in open hardwoods especially of oak, common in the Lower Peninsula in
midsummer if the weather is wet. Its favorite habitat appears to be
mossy areas near the edges of woodland pools, but on wet years it is
common in the oak-pine barrens around Topinabee.
Observations.-Although almost lacking in pigments, this is one of
our most attractive boletes when discovered in prime condition. The
pallid to glaucous pileus, pale stipe, and weakly yellowish tubes distinguish it in the field. It is frequently parasitized by a white mold. Smith
73112 represents a slender miniature variant of this species with a stipe
34 mm thick at the apex. For a discussion of variability of this species
in New England see Dick (1960).
Material examined.-Barry: Mazzer 4262, 4327, Aug. 1966; Smith
51178, 73122, 73160, 73184. Cheboygan: Charlton G 176; Shaffer
1924a; Smith 57330, 58147, 72404; Thiers 4383. Gratiot: Potter 3706,