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

360

THE BOLETES OF MICHIGAN

setiform caulocystidia are not present. The American taxa of this group
simply do not compare well with the most closely related taxa as described from Europe.
195. Boletus erythropus (Fries) Krombholz
Consp. Fung. Esc. p. 24. 1821
Dictyopus erythropus (Fries) Quelet, Enchir. Fung. p. 160. 1886.
Tubiporus erythropus (Fries) Ricken, Vadem. fur Pilzfreunde p. 205. 1918.
Illus. P1. 144.
Pileus 6-12 cm broad, convex, expanding to broadly convex, dry,
bright yellow on margin at times and disc yellow-brown ("argusbrown") to reddish ("Sanford's brown") varying to bay-red or rusty rose
but then with yellowish overtones from a faint bloom, retaining dark
brown to reddish tones in drying or becoming nearly date-brown; context greenish yellow, staining blue quickly when cut, FeS04 slowly
olivaceous, taste mild, odor none.
Tubes 10-12 mm deep, depressed around the stipe, bright yellow,
instantly bluish green when cut; pores minute, orange to orange-red,
often orange near the stipe and yellow near pileus margin, instantly blue
when bruised.
Stipe 6-10 cm long, 10-15 mm thick, equal, solid, yellow within,
instantly blue if injured and becoming olive to grayish olive slowly except for red base at least in the cortex; surface bright lemon-yellow and
minutely pruinose, pruina orange-cinnamon to red, surface blue where
handled, base with yellow mycelium and strigosity at times, rusty red in
the base as dried.
Spores 13-16 X 4.5-6 g, smooth, apical pore minute, color in
KOH ochraceous to ochraceous-brown, duller yellow-brown in Melzer's
(no amyloid reaction), shape in profile obscurely inequilateral to somewhat inequilateral, subfusoid in face view, wall about 0.2 u thick.
Basidia 4-spored, clavate, 8-11 ti wide. Pleurocystidia rare to
absent, 3447 X 8-13,, fusoid-ventricose, apex subacute, hyaline or
yellow in KOH. Cheilocystidia 21-32 X 6-9 p., subfusoid, ochraceous in
KOH. Caulocystidia 31-64 X 7-18 i, broadly fusoid to fusoid-ventricose,
not setiform or proliferated, apex subacute, thin-walled, content hyaline
or ochraceous (as revived in KOH), some cells vesiculose and up to 20,
broad.
Tube trama of the Boletus subtype, nonamyloid. Cuticle of pileus
of interwoven hyphae 3-5 u wide, with ends suberect at times (not a