258 EUNGXJS-PLOEA. 



In fir woods, &c. Plesli turning blackish or brown when 

 broken, resembling a Boletus with a scaly pilens. 



Pileus two inches broad, tesselated or cracked, like the 

 cone of the Scotch fir. Pores very white. Stem 3-4 in. 

 high, thick, solid. The stem is stated by Fries in his 

 specific character to be nearly smooth. Persoon describes 

 his species as sulcate, especially above, and furnished with 

 a downy veil. The stem in Dickson's figure is rough with 

 narrow erect scales. (Grev.) 



BOLETUS. Dili. 



Sporophore pileate, stem central; hymenophore inferior, 

 consisting of closely- packed, parallel, cylindrical or prismatic 

 tubes that are distinctly differentiated and readily separable 

 from the sporophore, openings or mouths of the tubes cir- 

 cular or angular (elongated and sinuous in the subgenus 

 Gyrodon) ; hymenium lining the cavities of the tubes, 

 basidia tetrasporous, spores large, elongato-fusiform, coloured. 

 Boletus, Dillenius, Fries, Obs. i. p. 109 ; Fries, Hym. Eur., 

 p. 495 ; Cke., Hdbk., p. 249. 



Annual. Usually large, pileus at first very convex or 

 pulvinate, fleshy ; either dry and more or less tomentose, or 

 at first viscid. Flesh in many species changing colour, 

 usually becoming blue when cut or broken. Stem central, 

 often very stout, in some species ornamented with thin 

 raised lines that anastomose to form a more or less -regular 

 network or reticulation, usually solid. In some species a 

 veil is present, that remains as a ring round the stem at 

 maturity. The tubes are easily removed from the pileus, 

 and the dissepiments or walls of the tubes — ^in reality the 

 tramal plates from which the hymenium proceeds — are in 

 some species coloured red at the opening of the pores. 



The peculiar property possessed by the flesh of some 

 species in becoming a more or less intense blue when cut 

 or broken, depends on the presence of two distinct substances 

 in the flesh; one, a resinous substance that becomes blue 

 when brought in contact with ozone; the other, a substance 

 sduble in^ water, which ozonises the oxygen of the air, and 

 then effects a combination with the resin, to which it gives 



