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

BOLETUS

317

32-54 X 8-15 j, fusoid-ventricose, thin-walled and smooth, apex acute,
content hyaline to yellowish when revived in KOH. Cheilocystidia
numerous, 20-32 X 8-12 u, fusoid to fusoid-ventricose, hyaline to
yellowish in KOH. Caulohymenium present in patches; caulocystidia clavate to subglobose, 35-60 X 10-30 L, thin-walled, smooth, soon hyaline
in KOH mounts.
Hymenophoral trama more or less divergent from a distinct central
strand of nongelatinous hyphae, the divergent hyphae gelatinous, central
strand hyaline to brownish in KOH; subhymenium subcellular to indistinct, of hyaline thin-walled cells.
Pileus cuticle a compact trichodermium the elements of which
have the distal 2-5 cells inflated to sphaerocyst proportions and some so
closely packed together as to produce a cellular layer, the cells (6)
10-24 M in diameter, more or less isodiametric and with yellow walls as
revived in KOH or in Melzer's. Hyphae of the context loosely interwoven, thin-walled, smooth, yellowish to brownish in Melzer's but content not distinctly colored. Clamp connections absent.
Habit, habitat, and distribution.-Scattered to gregarious under
hardwoods in a mixed forest or in pure stands of hardwoods, later
summer and early fall throughout the Great Lakes region, often abundant.
Observations.-This is reported as an edible species in the literature, but we have not tried it. It is abundant enough to warrant consideration as a worthwhile species if the flavor justifies it. Singer places
this species in Leccinum, but Smith and Thiers (1968) pointed out that it
lacks the major features of that genus. It lacks caulocystidia which
darken in age and the hymenophore is yellow. A large number of
boletes have caulocystidia so the mere presence of this type of cell
cannot be argued as indicating Leccinum; also, very few species of Leccinum have a yellow hymenophore when young, so the present species is
atypical to say the least as far as this feature goes. As amply pointed
out in this work, many boletes in various genera have inflated cells in
the elements of the pileus cutis.
170. Boletus sphaerocystis Smith & Thiers, sp. nov.
Pileus 5-7 cm latus, convexus, impolitus, cinnamomeus vel argillaceus. Contextus pallide luteus. Tubuli lutei, tactu subaurantiaci. Stipes
5-6 cm longus, 1-1.5 cm crassus, laete luteus, deorsum rufo-virgatus.
Sporae 14-18 X 5-6 p. Specimen typicum in Herb. Univ. Mich. conservatum est; prope Ann Arbor, September 15, 1961, legit Smith
64279.