PYRENOMYCETES 289 



The spores are colourless and one-celled, and in some 

 genera vary in number in different asci from the same 

 perithecium, a feature also common in the Tuberaceae. 



Distribution cosmopolitan. 



Perisporieae 



The perithecia are usually black, but in some genera, as 

 Eurotium, they are yellow or reddish. Many species are 

 parasites, occurring most frequently on leaves or fruit, 

 where they form black patches, or sometimes almost cover 

 the surface with a black film. Conidial forms are known. 

 The mould called Aspergillus is the conidial condition of 

 Eurotium. 



Most abundant in warm regions. 



Capnodieae 



All grow on living leaves, stems, or fruit ; they are most 

 abundant on coriaceous, persistent leaves, and last for 

 more than one season, when they form a thick, black crust, 

 and prove injurious, owing to preventing the action of 

 light on the surface of the leaves. As a rule, the species 

 are not parasites, but commence growth more especially 

 on leaves that are first covered with * honey dew.' Both 

 genera and species are imperfectly known. Several 

 conidial phases are known, whereas the ascigerous con- 

 dition is somewhat rare. 



Most abundant in warm regions. 



Sphaerieae 



In the simple forms the perithecia are free, either quite 

 superficial, partly immersed, or completely buried in the 

 matrix, the beak or ostiolum alone reaching to the surface. 



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