56 



ELEMENTARY STUDIES IN .BOTANY 



which on germination produce new mycelia, so that the 

 life-history of a mushroom is very simple compared with 

 that of a rust. 



These sporophores are not always of the umbrella-form 

 commonly associated with the name mushroom. Very often 

 they form brackets on stumps and tree trunks (Fig. 42) ; 



FIG. 42. A bracket fungus growing on a red oak. 



sometimes they are merely like incrustations; while in the 

 so-called " puff-balls " they are globular (Fig. 43). 



The groups of true Fungi. There are three great groups 

 of true Fungi recognized, which may be denned briefly as 

 follows. 



In the first group the mycelium has no cross walls, except as 



