Phylum:Basidiomycota >> Class: Basidiomycetes >>  Order: Boletales 
 BCRC Number NO BCRC Number!  
 Scientific Name: Xerocomus pulverulentus

Basionym: Boletus pulverulentus Opatowski, Wiegm. Archiv. Naturgesch. 2: 27. 1836.

Xerocomus pulverulentus (Opat.) Gilbert, Les Boletes, p.116. 1931.

 Description: Pileus 3-6 cm broad, convex to plane, even with uplifted margin in age, surface siccous, dull, velutinous to subtomentose, becoming glabrous when older, viscid when wet, color dark yellow-brown to blackish brown, margin entire, decurved, becoming plane or uplifted. Con-text soft and spongy, up to 1 cm thick or more, color yellow but changing to blue so rapidly as to obscure original color. Tubes 6-10 mm long, adnate to subdecurrent, yellow but instantly blue when bruised and slowly sordid brownish. Pores 1 mm broad at maturity, angular, color yellow, bluing quickly when bruised. Stipe 4-7 cm long, 1-2 cm thick, equal or nearly so, solid, bright yellow at the apex, changing to reddish brown and pubescent below, context yellow instantly turning blue when cut, surface of apex pruinose, not truly reticulate but often with raised lines, base blacking brown from handling. Spore print dark olivaceous to olive-brown. Spores 14-17.5 × 4-6.5 μm, fusiform-ellipsoid with blunt-ended or truncate. Basidia 28-45 × 10-11.5 μm, clavate, four sterigmata, 5-7 μm long. Pleurocystidia 45-70 × 10-16 μm, fusoid to clavate with elongated tapering apices, abundant, yellowish in KOH. Tube trama divergent from mediostratum which stains brown in KOH, hyphae 3-5 μm wide.

Taiwan, Taichung: Paikoutashan, alt. 1000m, 5 Jul 1995, Huang HW. 1267. Nantou: Sun Moon Lake, alt. 850m, 8 Sept.1994, Huang HW. 799; Shanlihsi, alt. 1750m, 17 Jun 1997, Chen CM. 1804.

 Habitat: Scattered or solitary under broad-leaved forest.

Taiwan, North America, Europe.


Chen, CM et al. 1997.


C. M. Chen

 Note: The species is intermediate between Boletus subtomentosus and B. badius but with many features not present in either of the two, such as the blackish brown pileus, the quick change to blue, the relatively broad pores and the dextrinoid context of pleurocystidia in Melzer,s reagent.