THE FUNCa WHICH CAUSE PLANT DISEASE 457 



The sporophores are borne in clusters in autumn on the ground 

 or on the bark. 



The spores, so^^-n in plum decoction, develop a mycelium which 

 soon produces rhizomorphs. These advancing give off delicate 

 hyphffi which may penetrate into the host. The mvcelium spreads 



Fig. 325. — Aiuiillaria mellea. After Clements. 



most rapidly through the medullary raj^s and from them into other 

 tissue elements. 



A. fuscipes Fetch causes a root disease of Acacia in Ceylon. 



A. mucida (Schrad.) Quel, is reported as a wound parasite of the 

 beech. 



Clitocybe Fries (p. 450) 



Pileus more or less fleshy, margin at first incurved; stipe fleshy, 

 often becoming hollow; gills decurrent. 

 About ninety species. Fig. 427. 



