DEVELOPMENT OF PLANTS 



247 



second from the end, will develop one or several asci (Fig. 157, 

 C, D). As in Penicillium, this growth becomes enveloped by a 

 mass of hyphae that originate from the hyphae bearing the 

 gametospore and from adjacent strands of the mycelium. These 

 ascocafps appear at maturity as black specks and in the majority 

 of forms they are provided with hair-like outgrowths that are 

 very regular and characteristic of the genera (Fig. 158). The 

 ends of these hairs are rather mucilaginous and may assist in 

 the dissemination of the ascocarps. The ascospores are resting 



FIG. 158. Forms of ascocarps found among the powdery mildews: A, 

 Phyllactinia with needle-like appendages enlarged at the base. B, Micro- 

 sphaera, appendages dichotomous at apex. C, Uncinula, appendages coiled 

 at apex. D, Erysiphe without appendages and crushed to show escaping 

 asci. E, an ascus containing six ascospores. 



spores adapted to enduring drought and cold as in Penicillium, 

 which they resemble in their discharge and germination. 



92. Reduced Ascomycetes. Space will only permit the 

 consideration of two other groups from this enormous alliance 

 of the Ascomycetes. These forms are here considered partly 

 because of their economic importance and partly because they 

 illustrate the reduction that may go on in the plant body. These 

 two groups of fungi have become so changed and simplified in 

 their structure and life history as to render impossible a guess 

 as to their relationship to other forms. 



