300 



BOTANY: PRINCIPLES AND PROBLEMS 



fructification. These are both chiefly saprophytic, the extensive 

 mycehiim penetrating deeply and under favorable conditions 

 producing at the surface very characteristic fructifications or 

 sporophores. 



A. Hymenomycetes. — These fungi are divided into a number of 

 orders, but by far the most important are the Agaricales or 

 agarics, which include the mushrooms and toadstools. This is a 



Fig. 176. — A gill fungus growing in a hollow tree. The mycelium penetrates 

 the wood in all directions and has produced the fruiting body here shown. In 

 cases like this it is sometimes hard to tell whether the fungus is a parasite or a 

 saprophyte. 



very large group and includes the most important of the so-called 

 "fleshy fungi". Because of the edibility of the sporophore of 

 many of its members and the poisonous character of a few of 

 them, the Agaricales have received intensive study and are per- 

 haps more widely known than any other fungi. 



The order is divided into a number of families according to 

 the type of fruiting body produced. In the Agaricaceae or gill 

 fungi (Figs. 175, 176, and 5) which are the mushrooms and toad- 

 stools proper, the hymenium covers the surface of plate-like 

 structures or gills. The sporophore in this group is the typical 

 "toadstool", which consists of a stalk or stipe supporting a broad 



