THE SAC FUNGI 6 1 



Order 3. Peronosporales. — Mildews, destructive parasites, living 

 in the tissues of their hosts and effecting pathologic changes. Ex.: 

 Albugo, the blister blight, a white rust attacking members of the 

 Cruciferae and Phytophthora, producing potato rot. 



Sub-class B. — Zygomycetes 



(Sexual apparatus shows isogamy) 



Order i. Mucorales, the black molds, mostly saprophytic. Ex.: 

 Mucor Mucedo, Rhizopus nigricans. 



Class II. — Ascomycetes, the Sac Fungi 

 Mycelium composed of septate filaments and life history character- 



Fig. 35. — A single perithecium of Clmiceps Fig. 36. — Asci contain- 



purpurea, magnified, showing the contained ing the long, slender asco- 

 asci. (From Sayre.) pores. (From Sayre.) 



ized by the appearance of a sac called an ascus in which ascospores are 

 formed. The largest class of fungi. 



Order i. Protoascales, the yeasts (Saccharomycetes) (position 

 doubtful). 



Order 2. Pezizales or cup fungi. Ex. : Peziza and Ascobolus. 



Order 3. Tuberales, the truffles. 



Order 4. Plectascales, the blue and green molds. Ex. : Aspergillus 

 and Penicillium. 



