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

BOLETUS

365

197a. Boletus separans var. subcaerulescens (Dick & Snell)
comb. nov.
Boletus edulis ssp. subcaerulescens Dick & Snell, Mycologia 57:455. 1965.
Pileus 5-12 cm broad, obtuse to broadly convex or nearly plane,
margin crenate-lobed forming sterile segments of tissue; surface glabrous,
uneven, moist but not viscid; color evenly dark vinaceous-brown ("walnut-brown") when young, more purplish brown in age. Context pallid,
pale vinaceous-buff near the cuticle; taste mild, odor none, no reaction
with FeSO4.
Tubes pallid, becoming dull yellow in age; depressed around the
stipe, up to 20 mm deep in largest pilei; pores stuffed when young,
becoming pale dull yellow and when bruised staining bluish but the stain
soon fading to yellow again.
Stipe 10-15 cm long, 2-3 cm thick at apex, enlarged downward,
pallid within, finally yellowish around wormholes, surface concolorous
with pileus (dark vinaceous-brown), becoming paler, reticulate overall
and reticulum near apex pallid, base with thin white mycelial covering
and not discoloring on bruising.
Spores 11-15 X 3.5-4.5 (5),p, smooth, wall slightly thickened, in
face view subfusiform, in profile inequilateral with a broad suprahilar
depression, somewhat ventricose in midportion, yellow in KOH, in
Melzer's yellow to pale yellow-brown. No fleeting-amyloid reaction
present.
Basidia 4-spored, 22-28 X 7-8 p, clavate, hyaline in KOH and
yellowish in Melzer's. Pleurocystidia-none seen. Many plate-like crystals
forming in KOH mounts. Tube trama so filled with laticiferous hyphae
as to obscure the arrangement of the matrical hyphae.
Pileus cuticle a palisade of clavate to cystidioid end-cells of trichodermial hyphae 2-3 cells long and 4-9 u wide, the end-cells 25-80 X
10-30,, some ventricose-mucronate, some fusoid-ventricose, and some
clavate, separating in KOH mounts as if subgelatinous, hyaline in KOH,
thin-walled, smooth. Context hyphae 8-15 p wide and hyaline to yellow
in KOH, large (to 15 p) laticifers very abundant and often lumpy and
contorted. Clamp connections absent. All tissues nonamyloid.
Habit, habitat, and distribution.-Scattered under birch, aspen, and
maple, near Pellston, July 29, 1961, N.J. Smith, collector (A. H. Smith
63749), and N. J. Smith, September 4, 1965.
Observations.-This variant was assigned to B. edulis originally, but
the cuticle of the pileus indicates that it is better placed here, and this is
correlated with the degree of pigmentation. The blue staining, however,
is an aberrant feature for either species.