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

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THE BOLETES OF MICHIGAN

in spite of the fact that the surface stains brown from being handled,
colored dots show slightly on the dried basidiocarps.
Spore deposit cinnamon as air-dried; spores 7-9 X 3 i, in profile
suboblong, to slightly inequilateral, in face view oblong or nearly so,
yellowish in KOH, in Melzer's dingy yellowish.
Basidia 4-spored. Pleurocystidia in clusters with vinaceous-brown
incrusting material when viewed as revived in KOH and also many cystidia
with colored content, hyaline when fresh but turning vinaceous with
KOH; individual cystidia cylindric to narrowly clavate, 34-45 (50) X
6-9 pL. Caulocystidia in massive clusters, the individual cystidia 50-90 X
7-12 i, when revived in KOH smooth and hyaline for the most part but
with the content finely colloidal and in KOH red only in the content in
the tip of the cell, smooth, pedicel flexuous, some surface hyphae with
reddish content in KOH also, and with reddish debris between the cells;
the red pigment in some clusters of cystidia slowly fading on standing in
KOH. Epicutis of pileus of gelatinous hyphae 2-5 p in diameter, hyaline
to yellowish in KOH. Clamp connections absent.
Habit, habitat, and distribution.-Scattered to gregarious under white
pine in a plantation at the University of Michigan Botanical Gardens in
October. It is known in Michigan only from the one locality.
Observations.-For comments on this species see Smith and Thiers
(1968). It is very easy to recognize by the sterile projecting margin of
the pileus, the droplets of latex on the young tubes, the fact that the
glandulae on the stipe do not darken as in S. granulatus, and that the
stipe stains yellow-brown to cinnamon on handling.
26. Suillus unicolor (Frost in Peck) Kuntze
Rev. Gen. PI. 3(2):536. 1898
Boletus unicolor Frost in Peck, Bull. N. Y. State Mus. 8:100. 1889.
Illus. PI. 31.
Pileus 4-7 cm broad, plano-convex, expanding to nearly plane,
thinly slimy viscid, perfectly glabrous or rarely with a few reddish dots
near the margin, color "empire-yellow" to lemon and constant for the
life of the basidiocarp. Context mild, odor not distinctive, when cut pale
to bright lemon-yellow, with KOH giving a flush of red and finally
bluish fuscous (the color change on the pileus surface similar).
Tubes decurrent, shallow (2-3 mm in young specimens, 5-6 mm in
mature ones), gelatinous, bright yellow, readily separable from pileus;
pores minute, bright yellow, not staining when bruised.