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

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THE BOLETES OF MICHIGAN

Observations.-The distinguishing features of this variety are centered in the hyphae of the trichodermium of the pileus rather than on
the naked stipe as the latter is viewed in the fresh condition. The content of the trichodermial cells, which is somewhat granular-colloidal in
appearance and colors ochraceous-orange in Melzer's, is distinctive, and
the hyphal proliferation from an occasional terminal cell reminds one of
B. hortonii. The colors are generally redder than in the type variety so
that the basidiocarps are frequently mistaken for B. truncatus when
collected. The type variety differs in the hyphae of the trichodermium
having more or less dark yellow-brown walls as revived in KOH. The
name B. versicolor is not available for this variant at the species level,
and we are not sure the European bolete to which the name is often
attached is identical with our variety.
Subsection FRATERNI Smith & Thiers, subsect. nov.
Pileus flammeus vel ruber, tactu caeruleus.
Typus: Boletus fraternus Peck.
Pileus red at first or if olive to olive-brown very soon becoming
red; context yellow or yellowish and staining blue when injured; tubes
yellow staining blue to greenish blue on injury; stipe naked to pruinosescurfy rarely faintly reticulate at apex.
KEY TO STIRPES
1. Stipe 1-3 cm thick near apex...................... Stirps Sensibilis
1. Not as above, usually 3-10 or rarely 13 mm thick........... StirpsFraternus
Stirps FRATERNUS
KEY
1. At least a fair number of the cells of the pilear trichodermium inflated and
with amyloid inclusions present in them or such inclusions present in some
of the noninflated cells also.....................B. B flavorubellus
1. Not as above....................................... 2
2. Spores 5-7 J. wide................. (see B. subfraternus also) 3
2. Spores 34.5 (5), wide............................. 4
3. Pores large (1 mm or more) and usually angular, KOH not causing a bright
yellow color in the terminal cells of the pilear cuticle........ B. fraternus
3. Pores 1-2 per mm, cuticular cells lemon-yellow in KOH...... B. campestris
4. Cuticle of pileus an epithelium but the cells not compacted into a
rigid layer................................B. harrisonii
4. Not as above....................................... 5