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

138

THE BOLETES OF MICHIGAN

of the subiculum hyphae of the stipe are also unusual and possibly characteristic. The colors are too pale for L. aurantiacum and the color
changes are not typical for that species.
64. Leccinum ambiguum Smith & Thiers, sp. nov.
Illus. PI. 67.
Pileus 6-15 cm latus, convexus, siccus, fibrillosus, sordide
olivaceo-brunneus. Contextus pallidus, tactu sordide cinnamomeus
demum violaceofuscus. Tubuli olivaceo-pallidi tactu sordide brunnei.
Stipes 6-15 cm longus, 1-2.5 cm crassus, clavatus, atrosquamulosus.
Sporae 14-17 X 4-5.5 u. Specimen typicum in Herb. Univ. Mich. conservatum est; prope Spectacle Lake, Chippewa County, July 13, 1968,
legit Smith 75571.
Pileus 6-15 cm broad, convex becoming nearly plane, with a distinct sterile margin which becomes broken into segments, surface dry
and appressed-fibrillose, not showing any separation of fibrils into
patches in oldest pilei; color olive-sepia (dull brown to grayish brown)
when young, nearly olive-buff in age or with browner areas where
bruised. Context pallid when cut, in buttons staining dingy cinnamon
and then lilac but slowly progressing to violaceous-fuscous, in mature
specimens staining lilac-fuscous directly; readily staining bluish on application of FeSO4.
Tubes pallid, soon olive-buff, depressed around the stipe; pores
very small (2-3 per mm), pallid young, becoming olive-buff and when
injured staining dull brown.
Stipe 6-15 cm long, 1-2.5 cm thick near apex, solid, clavate when
young; context changing color like that of pileus; surface of young
specimens with coal-black rather coarse ornamentation overall except
the whitish base, becoming more or less fibrillose-squamulose by maturity with the paler ground color showing, base remaining whitish.
Spores 14-17 X 4-5.5,, smooth, apex lacking a distinct pore,
shape in face view fusoid, in profile ventricose and narrowly inequilateral, color in KOH dull yellow-brown and in Melzer's not significantly
different, wall about 0.2-0.3 g thick, color in deposit not obtained.
Basidia 4-spored, about 30 X 10 g, hyaline in KOH and merely
weakly yellowish in Melzer's. Pleurocystidia scattered, 35-47 X 9-16 i,
fusoid-ventricose, apex pointed to subacute, content revived in KOH
hyaline to dull yellow-brown and in Melzer's hyaline to dark brown and
amorphous-but evenly distributed. Cheilocystidia subfusoid to clavate,
content often yellowish brown in KOH, 23-32 X 5-11 g. Caulocystidia