TYLOPILUS INDECISUS (Peck) Murrill, Mycologia 1:15. 1909
Boletus indecisus Peck, Ann. Rept. N.Y. State Mus. 41:76. 1888.
Illustrations: See Microfiche No. 53
Smith, A. H., and H. D. Thiers, The Boletes of Michigan, pl. 60.
Snell, W. H., and E. A. Dick, The Boleti of Northeastern North America, pl. 61.

Pileus 6-14 cm broad, convex to broadly convex when young, becoming plane to plano-convex to shallowly depressed on the disc with an undulating margin when mature; surface moist to dry, somewhat glistening but not viscid, becoming dull with age or when handled, cuticle firm, not soft, glabrous, rarely appearing subtomentose or velutinous; color dark brown ("hazel" to "Kaiser brown" to "russet" to "chestnut- brown") when young, becoming paler ("sayal brown" to "clay color" to "cinnamon-buff") with age, staining dark brown when bruised; margin incurved, becoming decurved, entire, becoming eroded. Context 1.5-3 cm thick, white when first exposed, unchanging or slowly darkening to pale brown ("clay color") near the cuticle and tan ("warm buff") elsewhere. Taste mild, sometimes slightly sweetish; odor mild.

Tubes 0.5-1 cm long, depressed, becoming somewhat decurrent with age, when young pink to pale flesh color ("avellaneous" to "cinnamon-buff" to "pinkish buff"), darkening slightly with age, staining brown when bruised or exposed; pores less than 1 mm broad, angular, concolorous with the tubes.

Stipe 8-10 cm long, 2-4.5 cm thick at the apex, equal to subclavate, white mycelium at the base, solid; surface dry, noticeably reticulate over three fourths of to entire length, buff to brown ("pinkish buff" to "cinnamon"), dark brown when bruised, reticulations concolorous or slightly darker than the surface. Context white when first exposed, changing to tan ("warm buff") in the apical region and vinaceous ("avellaneous" to "wood brown") toward the base.

Spore print flesh color. Spores 10.5-13 X 3-5 Ám, hyaline in KOH, hyaline to pale ochraceous in Melzer's, rarely dextrinoid, narrowly cylindric to ellipsoid in face view, ventricose in profile, walls smooth, thin.

Basidia 18-22 X 7-5 Ám, guttulate in KOH, hyaline, clavate, four-spored. Hymenial cystidia rare to scattered, inconspicuous, hyaline in KOH, reddish brown in Melzer's, clavate to fusoid-ventricose, sometimes appearing somewhat incrusted and then staining pale yellow in KOH.

Tube trama strongly divergent from a distinct central strand, hyaline, gelatinous in KOH, hyphae 6-8 Ám wide. Pileus trama interwoven, homogeneous. Pileus cuticle a tangled trichodermium with scattered erect hyphae, terminal cells not differentiated, not incrusted, reddish brown in KOH, hypodermium well differentiated and subgelatinous in KOH. Stipe cuticle differentiated as a palisade of caulocystidia and basidioles, staining brown in KOH. Clamp connections absent.

Chemical reactions KOH-cuticle black; NH4OH-cuticle red; HCL-cuticle yellow brown; FeSO4-stipe dark gray, pileus context gray, cuticle black; guaiac-positive on all parts.

Habit, habitat, and distribution Scattered to gregarious in soil under live oaks in the coastal foothills. Known only from the Green Valley area in Solano County. Although relatively common in the midwestern and eastern United States, so far as is known this is the first report of its occurrence west of the Rocky Mountains.

Material studied Solano County: Thiers 24508, 26998.

Observations Tylopilus indecisus is easily distinguished from other Tylopilus species occurring within the state by the well-developed, expanded pileus, the strongly reticulate stipe, and the flesh-colored rather than dark-brown pores. The nonamyloid spores further distinguish it from T. amylosporus.

Edible.

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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