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

SUILL US

53

brown pigment around the base, 33-52 X 6-8 j, content hyaline or
coagulated and yellowish (when revived in KOH). Cheilocystidia in large
clusters with copious brown amorphous pigment surrounding the base of
the cluster; individual cystidia 50-90 X 6-10 u, narrowly clavate,
smooth, mostly with dark yellow-brown content, yellow-brown pigment
often pervading throughout the cheilohymenium. Caulocystidia in large
clusters, with amorphous brown pigment around the clusters; single
cystidia 50-100 X 5-10 u, narrowly clavate to narrowly fusoid-ventricose, some cylindric and flexuous, nearly all with dark brown content
revived in KOH. Caulohymenium mostly with basidia paler than the
cystidia but still colored and with amorphous pigment throughout the
layer; subhymenium gelatinous.
Tube trama of somewhat divergent gelatinous hyaline hyphae.
Epicutis of pileus a layer of widely spaced interwoven branched gelatinous hyphae 2-5 / wide, yellowish in KOH, apparently trichodermial in
origin; hypodermal area dark bister in KOH. Clamp connections absent.
Habit, habitat, and distribution.-Under conifers (spruce, fir, and
pine), but with birch and aspen in the stand also, late summer and fall,
apparently rare, Smith 72488 and the type (Smith 57893).
Observations.-This is a peculiar species because of the strong yellow staining reaction of the base of the stipe, the pale yellow tube
mouths when young, the scattered pleurocystidia and gigantic cheilocystidia. In the pores it resembles S. luteus. In the tube trama near the
pores the tramal hyphae of the central strand are often yellow-brown
the same as the cheilocystidia.
15. Suillus acidus (Peck) Singer
Farlowia 2:271. 1945
Boletus acidus Peck, Bull. N. Y. State Mus. 105:15. 1906.
var. acidus
Illus. P1. 18.
Pileus 3-10 cm broad, obtuse becoming convex, glutinous from a
thick slime layer, glabrous, not streaked beneath the slime, white at first
as in S. placidus, the slime soon yellowish and pileus becoming tinged
greenish yellow, in age near "Naples-yellow" or finally "pale pinkish buff'
(yellowish white), slowly developing brownish discolorations where
bruised. Context pallid, odor slight, taste of pellicle decidedly acid, with
KOH lilaceous, with FeS04 grayish olive, with Guaiac no color change.