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

BOLETUS 303
KEY TO SPECIES
1. Context of pileus when cut or broken changing to blue instantly........ 2
1. Context changing more slowly or not changing................... 3
2. Pileus lemon-yellow at first; pores 1-2 per mm..... B. pseudosulphureus
2. Pileus dark yellow-brown to blackish brown; pores 1-2 mm in
diameter.............................. B. pulverulentus
3. Taste of pellicle bitter; spores 8-10 x 4-5 B............... B. calvinii
3. Not as above....................................... 4
4. Pileus whitish when young, becoming slowly leather-brown; NH40H
on cuticle no reaction.......................... B. pallidus
4. Pileus yellow-brown, gray-brown, smoky buff, or cinnamon to
bay-red....................................... 5
5. Pileus dry, bay-red; spores merely yellowish as revived in Melzer's....................................... B. albocarneus
5. Not as above....................................... 6
6. Stipe clavate, 1-3 cm thick above, up to 5 cm at base before expanding; pileus dingy cinnamon.................. B. huronensis
7. Pileus bay-red, NH40H olive to green around the spot of application (on
fresh caps); spores greenish as revived in Melzer's.............. B. badius
7. Pileus alutaceous to smoky buff; NH4OH not giving an olive to green reaction on pileus (?)............................. B. glabellus
160. Boletus calvinii Smith & Thiers, sp. nov.
Pileus 5-10 cm latus, convexus, viscidus, ferruginus. Contextus
albidus, immutabilis. Tubuli lutei tactu subviridis. Stipes 4-6 cm longus,
6-15 mm crassus, sursum rufus, deorsum sordide brunneus, non-reticulatus. Sporae 8-10 X 4-5 a. Specimen typicum in Herb. Univ. Mich.
conservatum est; prope Ann Arbor, August 14, 1915, legit C. H.
Kauffman.
Pileus 5-10 cm broad, convex, with a viscid pellicle, glabrous,
even, "chestnut" to "hazel" (ferruginous), surface bitter to the tongue.
Context white, scarcely changing color when bruised, 5-12 mm thick.
Tubes adnate, at length depressed, 10 mm deep, yellow ("Martiusyellow") and at length greenish (almost "olive-lake"); pores angular
about 1 mm broad, concolor with sides, surfaces slowly greening where
bruised.
Stipe 4-6 cm long, 6-15 mm thick, tapering downward or subequal, rufous to near apex, at length smoky brown toward the base,
solid, not reticulate, apex pallid, faintly pruinose, subpunctate toward
the base.