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

BOLETUS

355

Pileus 12 cm broad, broadly convex; surface dry and appressedfibrillose, unpolished, dark rose-red at maturity and dark rose-bay as
dried. Context pallid, when cut the surface quickly stained violaceous.
Tubes "ochraceous-buff' to more croceus, staining violet when
bruised, 12 mm long, depressed around the stipe; pores minute, flamescarlet staining bluish olive.
Stipe about 10 cm long, 15 mm thick, equal, within dark red with
yellow streaks, staining violet on cut surface; exterior surface lacking
any distinct basal mycelium, rose-pruinose above and in upper third with
longitudinal lines which darken in drying, not reticulate.
Spores 12-16 X 5-6.5 Ju, smooth, with a minute apical hyaline
spot, wall about 0.3 / thick, in profile inequilateral-elongate, in face
view somewhat fusiform, dingy ochraceous-brown, near bister in Melzer's
(amyloid when fresh but changing on drying).
Basidia 4-spored, clavate, 8-11 u broad. Pleurocystidia 38-63 (120)
X 9-14 u, fusoid-ventricose with narrow elongated flexuous neck,
content often dark yellow-brown in KOH and darker (dark sepia) in
Melzer's. Cheilocystidia 21-32 X 3-6 u, narrowly subfusoid to narrowly
clavate, the palisade ochraceous in KOH. Caulocystidia fusoid-ventricose
and 28-50 X 9-13 j with the neck often flexuous and apex subacute, or
the cell setiform to narrowly ventricose at base and with a long-tapered
neck to over 100, long which in some is furnished with one or more
short protuberances or branches, some with a secondary septum distal to
the ventricose portion, wall smooth and thin, context and wall hyaline
to ochraceous in KOH. Subiculum hyphae also hyaline but those of
cortex when mounted in KOH quickly very dark brown but slowly
fading to pale brown, the walls smooth and thin but colored.
Cuticle of pileus a matted layer of hyphae 2-4 / wide, with bright
red content in KOH when fresh but soon fading to hyaline, in Melzer's
as revived the content pinkish red and the color persistent, content of
subcuticular and tramal hyphae not distinctive in Melzer's. Clamp connections none.
Habit, habitat, and distribution.-Solitary under low hardwoods,
Ann Arbor, September 20, 1965, collected by Florence Hoseney (Smith
72668).
Observations.-The distinguishing features of this species are the
greatly elongated pleurocystidia-reminding one of the caulocystidia, the
red content of the cuticular hyphae as revived in Melzer's and the dark
brown reaction of the hyphae of the cortex of the stipe when revived in
KOH. In the field when fresh the longitudinal striations over the upper
part of the stipe, the dark red pileus and whitish (pallid) flesh are
distinctive. It is close to B. luridellus, but the latter has very small
pleurocystidia and bright lemon-yellow flesh.