FUNGI AND FUNGOUS DISEASES OF PLANTS 257 



earth, decaying wood (fig. 183), or other nourishing material. 1 

 In its growth the mycelium helps to effect decay, and may 

 thereby enrich soils, or, in the case of mushrooms that grow upon 

 living trees, it may hasten their destruction. At times aggre- 

 gations of the mycelium are formed ; these are whitish, bud- 

 like growths (called buttons), which are the beginnings of the 



FIG. 199. The "shaggy mane" mushroom (Coprinus comatus) 



At the left of the main group is one young mushroom just emerging from the soil. 



The tallest plant in the photograph was 9i inches high. From A. H. R. Buller's 



" Researches on Fungi " 



mushrooms. They grow and push their way to the surface. 

 As the button elongates, its top begins to expand into the 

 umbrella-like form, and finally opens out as the crown, or 

 pileus, with its center attached to the upper end of the stalk 

 (stipe) (figs. 199 and 200). As the pileus opens, it is joined 



1 " The Principles of Mushroom Growing and Spawn Making," Bulletin 85, 

 Bureau of Plant Industry, U.S. Dept. Agr., 1905. The United States De- 

 partment of Agriculture publishes several bulletins upon poisonous and 

 edible fungi. 



