ASCOSPORES 



ASCUS 



HYPHAE 



Fig. 31-10. Asci and ascospores are distinctive of 

 the sac fungi, or Ascomycetes. (From The Plant World.) 



spores (ascospores) are produced from a sin- 

 gle diploid spore mother cell. Typically the 

 appearance of an ascus follows immediately 

 after sexual reproduction, when two gamete 

 nuclei fuse to form the diploid nucleus of 

 the spore mother cell. The cells of the myce- 

 lium, which grows from an ascospore, are 

 haploid and the haploid condition endures 

 throughout most of the life cycle in Ascomy- 

 cetes generally. 



In many species the asci are formed more 

 or less individually at the ends of certain 

 hyphae. But in others the ascal sacs are 

 borne by a highly organized fruiting organ, 

 called the ascocarp. In fact, many of the spe- 

 cies are best identified on the basis of the 



The Plant Kingdom - 605 



size, shape, and color of their ascocarps, as is 

 shown for a cup fungus, in Figure 31-11; and 

 for the sponge fungus, in Figure 31-12. 



Ascomycetes do much harm, through the 

 spoilage of foods, tobacco, fabrics, and so 



Fig. 31-12. Some Ascomycetes are called sponge 

 fungi, or morels. This one (Marchella escu/enfa) is 

 edible. Moreover, it is considered a rare delicacy. 

 (Photo by C. F. Hottes; from The Plant World.) 



i 



j 



Fig. 31-11. Some Ascomycetes, such as this one (Peziza), are called cup fungi, 

 owing to the shape of the ascocarp. (From The Plant World.) 



