PULVEROBOLETUS RAVENELII (Berkeley and Curtis) Murrill, Mycologia 1:9. 1909
Boletus ravenelii Berkeley and Curtis, Ann. Mag. Nat. Hist. II, 12:429. 1853.
Illustrations: See Microfiche No. 36
Smith, A. H., and H. D. Thiers, The Boletes of Michigan, pls. 149-150
Snell, W. H., and E. A. Dick, The Boleti of Northeastern North America, p1. 29.

Pileus 5-13 cm broad, convex to subglobose when young, becoming convex to broadly convex to plano-convex at maturity; surface viscid to subviscid but typically overlain with a dry veil, tomentose to pulverulent due to velar layer, glabrous to appressed fibrillose when veil fragments disappear, sometimes appearing fibrillose-scaly or eventually rimose-areolate when very old; background color typically pinkish to orange brown ("pale pinkish buff" to "pinkish cinnamon") with fibrils or streaks of reddish brown ("Hays russet" or "russet"), but background may be as pale as buff color ("light buff") or brown ("cinnamon"), veil elements colored intensely yellow ("wax yellow" to "strontian yellow") in young basidiocarps, unchanging or becoming a paler yellow ("light greenish yellow" to "greenish yellow") when old; margin incurved, entire but often appendiculate with veil fragments. Context 1-2 cm thick, whitish to pale yellow ("ivory yellow" to "pale pinkish buff"), slowly changing to blue when exposed, sometimes becoming brown or yellow when exposed. Taste somewhat acid; odor not distinctive.

Tubes 0.5-1.5 cm long, adnate, becoming slightly depressed to free with age, bright yellow ("primuline yellow" to "lemon yellow") when young, becoming darker yellow ("buffy citrine" to "olive lake" to "chamois") with age, turning blue to greenish blue when bruised, sometimes eventually changing to brown ("cinnamon-brown") to blackish; pores 0.5-1 mm broad, round to angular, concolorous with tubes, bluing when bruised.

Stipe 6-11 cm long, 0.7-1.5 cm thick at the apex, equal or occasionally tapering toward the apex or irregular in shape, solid, with white to pale yellow rhizoids at the base; surface dry to moist to occasionally subviscid, yellow ("primuline yellow"), typically covered with veil remnants colored bright yellow ("greenish yellow" to "strontian yellow" to "citron yellow"), sometimes appearing somewhat annulate. Context pale ochraceous to whitish except intensely yellow in base, unchanging or developing a pinkish tinge when exposed.

Spore print dark olive brown. Spores 8-11.2 X 4-6.4 µm, fusoid to ovoid to subellipsoid, ochraceous in KOH with a hyaline outer sheath, ochraceous tawny in Melzer's, smooth, moderately thick walled.

Basidia 24-35 X 10-14 µm, four-spored, hyaline, clavate. Hymenium typically yellow in KOH. Hymenial cystidia 30-56 X 5-12 µm, scattered to numerous, often somewhat embedded in the hymenium, hyaline to lemon yellow in KOH, clavate to fusoid to subcylindric, thin-walled.

Tube trama strongly divergent from distinct central strand, hyaline, gelatinous in KOH. Pileus trama interwoven, homogeneous. Pileus cuticle differentiated as a trichodermium of interwoven hyphae. Veil tissue composed of a mass of narrow, loosely interwoven hyphae staining yellow in KOH, no sphaerocysts apparent. Stipe cuticle similar to that of the pileus. Clamp connections absent.

Chemical reactions HNO3-context pink, cuticle pink.

Habit, habitat, and distribution Solitary in humus in mixed forests of coastal regions. Most commonly found under oaks. Fruiting during fall and winter rainy season. As far as can be determined, this is the first report of this species from the state and possibly from the entire Pacific coastal area.

Material studied Del Norte County: Thiers 21540. Mendocino County: Ripley 899; Thiers 9331, 9350, 9439, 10636, 11023, 21398, 21507, 21528, 26896.

Observations It is very difficult to confuse this bolete with any other. It is readily recognized by the cottony, bright yellow veil, which, when young, envelops the entire basidiocarp. When older or after heavy rainstorms the veil, to a large extent, is likely to disappear; however, there are usually surviving fragments on the stipe or margin of the pileus that indicate its presence. The structure of the veil is interesting in that it does not possess any of the large, rounded cells (sphaerocysts) frequently seen in veils of other species.

Edibility unknown.

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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