122 THE POLYPORACfEAE OF WISCONSIN. 



15. BOLETUS (Dill.) Linn. 



Carpophore consisting of pileus with a central stipe, of fleshy con- 

 sistency, putrescent. Tubules composing a stratum which is easily 

 separable from the pileus, and the tubes also easily separable from each 

 other. 



Series 1. Tephroleuci. Tubes at first white or gray. 



A. Cariosi. Stipe not reticulated, cavernous or stuffed within 

 Tubes wMte sometimes becoming yellowish. 



Boletus castaneus Bull. (Plate XXV, fig. 84). 



Pileus convex, nearly plane or depressed, firm, even, dry, minutely 

 velvety-tomentose, cinnamon or reddish-brown, flesh white, unchange- 

 able ; tubes free, short, small, white becoming yellow, stem equal or tap- 

 ering upward, even, stuffed or hollow, clothed and colored like the pi- 

 leus, spores 10 to 12.5 microns long, 6 to 7.6 microns broad. Pileus 3 to 

 8 cm. broad ; stem 2.5 to 6 cm. long, 6 to 12 mm. thick. 



Peck says, (21, 2, 8 p. 156) : "The pileus and stem are often reddish- 

 brown or chestnut colored, but sometimes they are paler, inclining to 

 tawny or cinanmon hues. The thin margin sometimes curves upward 

 and then dried specimens resemble B. Roxanae. The plant has been re- 

 corded as edible." 



Common everywhere about Madison, Blue Mounds and Devil's Lake. 

 Found also near Ladysmith, and probably widely distributed in the 

 state. Largest specimen measuring 10 cm. broad, stipe about 10 cm. 

 long and about 1 cm. thick. Some stems are hollow and some stuffed. 

 Occasionally the plants are cespitose, making groups of two or three or 

 more. 



On drying, the thin margins of most specimens curve upward, espe- 

 cially in older specimens. The pores in most specimens are scarcely 

 medium, more or less free, yellowish or reddish-yellow in color. The 

 tubes are usually short but become longer and larger with age. In old 

 specimens the color of the tubes becomes almost cinnamon. 



The species may be recognized by its color, its cavernous or stuffed 

 stem and the thin, upcurving margin. 



