THE FUNGI WHICH CAUSE PLANT DISEASE 133 



Pezizales (p. 123) 



In this order unlike the last, the hymenium is at first enclosed 

 but soon becomes exposed. The apothecia at maturity are typi- 

 cally disc or saucer-shaped (Fig. 101) or sometimes deeper, as 

 cup, beaker or pitcher-shaped. They vary from a size barely 

 visible up to 8-10 cm. in diameter. Some are stalked, more often 

 they are sessile. In consistency they vary from fleshy or even 

 gelatinous to homy. Paraphyses are present and may unite over 

 the asci to form a covering, the epithecium. The apothecium may 

 be differentiated into two layers; the upper bearing the asci is the 

 h3rpotheciuin, the lower the peridium. In some cases sclerotia 

 are formed. Many species possess conidiospores as well as asco- 

 spores, borne either on hyphse or in pycnidia. The great majority 

 are saprophytes, a few are parasitic. There are some three thou- 

 sand species. 



Key to Families of Pezizales 



No lichenoid thallus and no algal cells 

 Ascocarps free, solitary or cespitose 

 Ascocarps fleshy or waxy, rarely gelati- 

 nous; ends of paraphyses free 

 Peridium and hypothecium without 

 distinct lines of junction 

 Ascoma open from the beginning, 

 convex; peridium wanting or 



poorly developed 1. Pyronemaceffi. 



Ascoma concave at first; a fleshy 

 peridium present. 

 Asci forming a uniform stratum, 



at maturity not projecting. 2. Pezizaces. 

 Asci projecting from the ascoma 



at maturity 3. Ascobolacese. 



Peridium forming a more or less dif- 

 ferentiated membrane. 

 Peridium of elongate, parallel 

 pseudo-parenchymatous, hya- 

 Ime, thin-walled cells 4. Helotiacese, p. 134. 



