17-J STUDIES OF AMERICAN FUNGI. 



Tubes or pores shallow, formed by a network of 

 folds or wrinkles, plants thin, sometimes spread 

 over the wood, and somewhat gelatinous, . . Merulius. 

 2 Mass (stratum) of tubes easily separating from the 

 cap when peeled off, cap not with coarse scales, 

 tubes in some species in radiating lines, .... Boletus. 

 Stratum of tubes separating, but not easily, cap 



with coarse, prominent scales, Strobttomyces. 



Stratum of tubes separating, but not easily, tubes 

 arranged in distinct radiating lines. In one 

 species (B. porosus) the tubes do not separate 



from the cap, Boletinus. 



This last genus is apt to be confused with certain species of Bo- 

 letus which have a distinct radiate arrangement of the tubes. It is 

 questionable whether it is clearly distinguished from the genus 

 Boletus. 



BOLETUS Dill. 



Of the few genera in the Poh'poracece which are fleshy and pu- 

 trescent, Boletus contains by far the largest number of species. The 

 entire plant is soft and fleshy, and decays soon after maturity. The 

 stratum of tubes on the under side of the cap is easily peeled off and 

 separates as shown in the portion of a cap near the right hand side of 

 Fig. 169. In the genus Polypoms the stratum of tubes cannot thus 

 be separated. In the genera Strobilomyccs and Boletinus, two other 

 fleshy genera of this family, the separation is said to be more diffi- 

 cult than in Boletus, but it has many times seemed to me a <( dis- 

 tinction without a difference." 



The larger number of the species of Boletus grow on the ground. 

 Some change color when bruised or cut, so that it is important to 

 note this character when the plant is fresh, and the taste should be 

 noted as well. 



Boletus edulis Bull. Edible. \_Ag. bulbosiis Schaeff. Tab. 134, 1763. 

 Boletus bulbosus (Schaeff.) Schroeter. Cohn's Krypt, Flora. Schles- 

 ien, p. 499, 1889]. This plant, which, as its name implies, is edible, 

 grows in open woods or their borders, in groves and in open places, 

 on the ground. It occurs in warm, wet weather, from July to Sep- 

 tember. It is one of the largest of the Boleti, and varies from 5-12 

 cm. high, the cap from 8-25 cm. broad, and the stem 2-4 cm. in 

 thickness. 



The pileus is convex to expanded, smooth, firm, quite hard when 

 young and becoming soft in age. The color varies greatly, from 



