THE FUNGI : ASCOMYCETES AND BASIDIOMYCETES 299 



Fig. 290. — Piiccinia poarum. Group of cluster 

 cups in surface view on leaf of Tussilago 

 farfara. 



_ Pycnidium 



Aecidium 



Fig. 291. — Piiccinia graminis. Transverse section of leaf 

 of Barberry showing pycnidia on upper surface, and 

 aecidia on lower surface, discharging aecidiospores. 

 The tissues of the leaf are hypertrophied. 



