Gastrocarps 3-5 cm broad, convex, becoming highly irregular in outline, typically boletoid in appearance; peridium dry, relatively thin, surface with numerous pits and wrinkles, tomentose to velutinous; color brown ("mummy brown" to "chestnut-brown"), characteristically with reddish or yellowish tints or spots with age; margin incurved to decurved, highly irregular. Context 3-7 mm thick, yellow, changing to blue when exposed. Taste and odor mild.
Gleba tubulose, tubes 1.5-3 cm in length, highly irregular and sinuous in arrangement, never truly vertical, broadly depressed around the stipe-columella; color yellow ("greenish yellow"), changing to blue when bruised; pores 0.5-1 mm broad, angular, typically pink to red, bluing when bruised.
Stipe-columella 2-4 cm long, 1-2 cm thick at the apex, typically equal, except narrowed at the base, often not extending much beyond the gleba, solid; surface dry, yellow but often covered with small reddish scales or granules, glabrescent. Context yellow, changing to blue when bruised.
Spores 13.5-15.5 X 7.5-8.5 Ám, fusoid to subellipsoid in face view, slightly inequilateral in profile, ochraceous in KOH, walls 0.5-1 Ám thick, smooth, often with slight germ pores.
Basidia 25-37 X 8-12 Ám, hyaline in KOH, guttulate, clavate, four-spored. Hymenial cystidia 40-58 X 8-15 Ám, uncommon, inconspicuous, clavate to cylindric to fusoid, hyaline, thin-walled.
Tube trama obscurely divergent, hyaline, hyphae 3-5 Ám wide. Peridial trama hyaline, interwoven, homogeneous. Peridial cuticle differentiated as an appressed to tangled layer of hyphae, 4-5 Ám wide, contents staining bright brown in KOH, walls not incrusted. Clamp connections absent.
Habit, habitat, and distribution Scattered to gregarious in soil under conifers. In this state it is known only from higher altitudes, where it appears to be associated with red and white fir.
Material studied Calaveras County: Thiers 21252, 21256. Lassen County: Kowalski 3835. Sierra County: Thiers 23648, 23649, 23650, 23652, 23960. Siskiyou County: Cooke 38660, 38661.
Observations This was the first gastrobolete known from North America and appears to be widely distributed throughout the temperate conifer forests of the continent. It is recognized by the brown cap with yellow to red spots or flushes, the consistent blue discoloration of the context when bruised, and the large, thick-walled spores, which are neither truncate nor amyloid.
The Boletes of California
Copyright © 1975 by Dr. Harry D. Thiers
Additional content for the online edition © 1998 by Michael Wood, Fred Stevens, & Michael Boom
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