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

LECCINUM

179

85. Leccinum rotundifoliae (Singer) Smith, Thiers, & Watling
Mich. Bot. 6:128. 1967
Krombholzia rotundifoliae Singer, Schw. Zeitschr. Pilzk. 16:148. 1938.
Pileus 2-6 cm broad, obtuse to convex becoming broadly convex,
margin not appendiculate, dry at first and unpolished, becoming somewhat viscid by maturity, white to dull white overall at first, slowly
becoming pale buff to pinkish buff then cinnamon-buff to dingy clay
color, rimulose in age at times or on drying. Context white, showing no
appreciable color change when sectioned and pallid when properly dried,
with FeSO4 blue both in pileus and stipe; odor and taste not distinctive.
Tubes 10-15 mm deep, white to olive-buff, slowly becoming pale
wood-brown by maturity, unchanging when cut or bruised; pores small,
2-3 per mm, whitish becoming avellaneous.
Stipe 4-10 cm long, 5-12 mm at apex, equal or nearly so, white
and roughened from white scabrosity which slowly becomes brown like
the pileus but was never seen to become blackish, solid, white within
when cut, soon greenish blue in the base and brownish in the apex, as
dried with a faint yellow tone over basal half in some.
Spores 16-20 (25) X 5.5-7.5 (8) u, smooth, narrowly subfusoid to
elongate-subovate in face view, very obscurely inequilateral in profile,
the suprahilar depression often very indistinct, pale ochraceous to
brownish ochraceous in KOH, many soon becoming dextrinoid when
revived in Melzer's, wall thickened slightly, no distinct pore present at
apex.
Basidia 4-spored, 23-28 X 9-13 a, hyaline to yellow in KOH.
Pleurocystidia 28-36 X 8-14 pu, more or less fusoid-ventricose, hyaline or
nearly so. Cheilocystidia versiform but mostly fusoid-ventricose, 32-60 X
8-12 u, the neck tapered and flexuous or irregular in outline, ending in
an acute to subacute apex, with lemon-yellow content in KOH.
Pileus trichodermium consisting of tangled mostly thin-walled flexuous narrow hyphae with hyphal ends 3-5 j wide, subgelatinous in
KOH, with yellow-brown content, often flexuous, the tips of the cells
obtuse to subcapitate and merely dull yellowish to orange-buff in
Melzer's. Hyphae of the context 8-15 u wide, with "colloidal" content
in KOH causing them to be very boldly defined as seen under the
microscope, hyaline in KOH but in Melzer's reddish to brownish red and
the color located in the content which remains homogeneous. Clamp
connections absent.