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

166 THE BOLETES OF MICHIGAN
and forms identified in the following key. The term "form" is used in
the sense of variant, not in its formal sense.
KEY
1. Pileus yellow or orange-yellow, at times with a sparse overlay of slightly
grayish fibrils............................... f. ochraceum
1. Pileus some other color................................. 2
2. Pileus dull orange-brown; stipe ornamentation dingy yellow-brown;
spores 4.5-5.5 (6) u......................... f. obscurum
2. Pileus more orange shading to red; stipe ornamentation soon dark
brown...................................... 3
3. Pileus typically conspicuously fibrillose-squamulose when mature or older,
margin rusty orange, disc rusty red................... f. squamosum
3. Pileus more or less fibrillose to squamulose when young; usually glabrous
in age........................................... 4
4. Tubes becoming yellowish before the darkening of maturity...................................var. luteopallidum
4. Tubes lacking a yellow stage........................... 5
5. Stipe ornamentation remaining reddish brown for some time before becoming blackish; pileus ferruginous brown.................. f. lateritium
5. Pileus distinctly orange-red or brighter........................ 6
6. Pores staining dingy brown when lightly bruised.......f. subferrugineum
6. Pores yellowish then olive when lightly bruised............ f. insigne
81a. Leccinum insigne var. luteopallidum, var. nov.
A typo differt: Tubuli luteolae. Typus: Smith 71745 (MICH).
Pileus about 8 cm broad, convex, margin appendiculate, surface
dry, near the margin with appressed fibrils, elsewhere merely uneven;
color dull ferruginous ("cinnamon-rufous") to orange-tan, drying to a
dark wood-brown (gray-brown). Context pallid, when cut soon flushed
with fuscous streaks in the stipe apex and becoming black in drying.
FeS04 on fresh context bluish, with KOH brownish; odor mild;taste
acid then mild.
Tubes about 1 cm long, depressed around the stipe, pale yellow
young ("ivory-yellow" or slightly brighter), with KOH dull cinnamon,
dull brown where cut; mouths minute, yellowish, slowly staining snuffbrown when lightly bruised, when severely bruised violaceous-fuscous.
Stipe about 13 cm long, 2 cm thick, equal or at first evenly
enlarged downward, pallid within, when cut showing greenish blue
streaks, slowly staining fuscous generally, with NH40H or KOH yellow