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

268

THE BOLETES OF MICHIGAN

Basidia 4-spored or 1-, 2-, and 3-spored also. Pleurocystidia scattered, 36-63 X 9-18 #j, fusoid to ventricose-subcapitate, content when
revived in Melzer's orange brownish and amorphous, fading on standing,
walls smooth and thin. Caulocystidia in fascicles or scattered, 18-32 X
9-15 gt, content ochraceous in KOH and the same for the cortical
hyphae of the stipe.
Pileus cutis a tangled trichoderm of hyphae 6-12 (15) u wide, with
the last 3-4 cells short and becoming inflated to elliptic or subglobose,
the end-cell cystidioid to subglobose, content ochraceous in KOH, paler
in Melzer's, no amyloid material present, walls thin and smooth or
nearly so. Subcuticular and tramal hyphae finally nearly hyaline in
Melzer's but fleeting-amyloid reaction strong and relatively persistent, no
dextrinoid incrustations seen on any of the hyphae. Context hyphae
often with "colloidal" content in Melzer's but their color merely yellowish.
Habit, habitat, and distribution.-Gregarious in grass near a spruce
tree, Ann Arbor, July 11, 1967, K. A. Harrison 9504.
Observations.-Although described from a single collection the
positive features of this species are sufficient to justify describing it. The
inflated cells in the pileus trichodermium are so numerous that in sections of mature pilei one is reminded of an epithelium with the cells
loosely arranged. The ultimate cell in a filament is often "aborted"possibly formed secondarily by a cross wall in the original apical cell at
the point where the taper begins. The pleurocystidia are large and conspicuous in mounts revived in Melzer's. The spores vary greatly. In some
basidiocarps small ellipsoid spores 8-10 X 4-5 u are present along with
the typical range (9-12 X 4.5-5.5,u), and in all caps a varying number of
larger spores was present. The species is close to B. fraternus, but the
almost epithelial structure of the cuticle of the pileus distinguishes it
from all in this group.
141. Boletus rubellus Krombholz
Nat. Abb. Sche. 5:12. 1836
var. rubellus
Illus. Fig. 81.
Pileus 3.5-8 cm broad, broadly convex expanding to plane or margin finally uplifted; surface dry and plush-like when young, becoming
irregularly rimulose or in age distinctly areolate, color dull brick-red
with an olivaceous overtone, when dried distinctly brick-red in marginal
area and pale olive-brown over disc; margin even. Context pale flavous,
staining blue slightly when cut.