400 



DISEASES OF CULTIVATED PLANTS 



Most closely allied to Hypochmis, differing in being parasitic, 

 with immersed mycelium, and in the basidia bearing a variable 

 number of spores. 



Rhododendron galls (Exobasidium rhododendri, Cram.) 

 form on the living leaves of Rhododendron hirsutum, R. fer- 

 rugineum, R. Wilsonianum, etc., and vary in size from 



Fig. u;. Exobasidium rhododendri , on leaves of rhododendron, 

 slightly reduced; 2, basidia and sporrs of same, highly mag; 3, 

 Hypochnus solan i on lower part (if a potato haulm, slightly 

 reduced; 4. mycelium and basidia of Hypochnus, highly mag. 



a pea to that of a cherry. These arc at first pale green, at 

 length often becoming red or brownish. When full grown 

 the surface is covered with a delicate whitish bloom, due to the 

 presence of innumerable minute conidia, produced by budding 

 in a yeast-like fashion from the basidiospores. The mycelium 

 is very abundant between the cells at the periphery of the 

 gall, but scanty elsewhere. Small globose haustoria are 

 present in the cells of the host. 



basidia covering the surfare of the galls, clavatc, sterigmata 



1 



