3i8 A TEXTBOOK OF THEORETICAL BOTANY 



wood. Moreover, the hymenium is spread over the surface of very irregular, 

 rather fleshy ridges somewhat resembhng gills. The Fungus completely 

 destroys the lignin of the wood it attacks. Species oiFomes are also responsible 

 for the destruction of timber, either in the living state or after seasoning. 



Fig. 310. — Polyporus dryadeiis. Two fruiting bodies developed on Apple 

 showing the exudation of moisture from the pore surface. 



Fomes afinosiis, which attacks Pines, lives first as a parasite and later as a 

 saprophyte on the dead trees. 



Several species are used economically ; some are employed as food, e.g., 

 Fistnlitia hepatica (Beef Steak Fungus), which forms large fleshy brackets 

 on Oaks. Fomes officinalis was used medicinally because of the quinine-like 

 taste which it possesses. Fomes igniarius was once used to prepare high 

 quality tinder. 



Agaricales 



The Agaricales are Basidiomycetes in which the basidia are arranged over 

 the surface of plates of tissue called gills. These gills are borne radially, 

 arranged on the under surface of the fruiting bodies which generally consist 

 of a stalk and a cap. 



