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

BOLETUS

351

190. Boletus spraguei Frost
Bull. Buff. Soc. Nat. Sci. 2:102. 1874
"Pileus quite hard, very dark russet or brown, covered with a
minute velvety scurf. Tubes very minute, yellow ocher or brownish
when cut, around the mouths of a rich dark maroon color, which forms
a strong contrast with the light color of the stem, adnate when young.
Stem dark brown below, ochraceous at top, smooth above, minutely
velvety below, firm, fleshy, slightly constricted in the middle. Flesh
white, changing to blue, texture firm and fine. The rich color of the
pore mouths contrasting with the yellow stem, makes it quite distinct
from other species. Spores.0105-.0062 mm."
The original description is given above. The following data were
obtained from a Frost specimen at Albany, New York, in the Peck
collections.
Spore 9-12 X 3.5-5 JI, smooth, lacking apical differentiation; shape
in face view nearly oblong to narrowly elliptic, in profile obscurely
inequilateral, color in KOH nearly hyaline (mostly immature), yellowish
in Melzer's; wall thin. Hymenium mostly immature but basidia were
4-spored and 7-8 u broad. Pleurocystidia are present and measure 28-36
X 74-10, most are subfusoid and content not distinctive in KOH or
Melzer's; no amyloid reactions seen in or on hyphae or in the wall but
some "amyloid" debris present loose in the mounts.
Pileus cuticle a tangled mass of narrow hyphae 3-7 u wide, with
end-cells more or less ascending but not in a true palisade-becoming
decumbent as pileus enlarges; the hyphae tubular, cells long, content
yellowish in KOH, merely ochraceous in Melzer's and homogeneous,
walls thin and smooth, dextrinoid incrustations lacking. Hyphae of subcutis with dull yellow to orange-ochraceous content in Melzer's. Clamp
connections absent.
The following is a description of Michigan material (Smith 9613)
which we believe belongs here:
Pileus 7-13 cm broad, convex to nearly plane, margin even or
slightly wavy, surface dry and dull, minutely appressed-fibrillose under a
lens when mature, in age the surface layer cracking into minute or easily
visible areolae, color often "tawny" over center and yellow on the
margin but gradually becoming reddish brown overall, at times finally
"Prussian-red." Context yellow but changing to blue quickly when cut;
odor and taste not recorded.
Tubes about 1 cm deep, yellowish then quickly blue when bruised,
adnate to stipe when young, depressed somewhat in age; pores dark