THALLOPHYTES : FUNGI 



71 



has a stalk-like portion, the stipe, at the base of which the 

 slender mycelial threads look like white rootlets ; and an 

 expanded, umbrella-like top called the pileus. From the 

 under surface of the pileus there hang thin radiating plates, 

 or gills (Fig. 55). Each gill is a mass of interwoven fila- 

 ments (hyphae), whose tips turn toward the surface and 

 form a compact layer of end cells (Fig. 56). These end 



FIG. 60. A bracket fungus (Polyporus) growing on the trunk of a red oak. 

 CALDWELL. 



cells, forming the surface of the gill, are club-shaped, and 

 are called basidia. From the broad end of each basidium 

 two or four delicate branches arise, each bearing a minute 

 spore, very much as the sporidia appear in the wheat rust. 



