IMPERFECT FUNGI 239 



producing whitish or discolored spots, and eventually 

 developing small perithecia-like structures (pycnidia) 

 containing conidia. Species of Phyllosticta are common 

 on leaves of Virginia creeper, wild grape, cottonwood, 

 willow, pansy, peach, apple, wild cherry, elm, etc., while 

 species of Septoria are to be found on leaves of box-elder, 

 aster, thistle, evening primrose, wild lettuce, plum, 

 elder, etc. 



412. The Black-dot Fungi (Order Melanconiales) 

 differ from the preceding mainly in the absence of a 

 distinct perithecium, the spores developing beneath the 

 epidermis of the host and ])ursting through so as to form 



Fig. 115. — Septoria. Fig. 116. — Fig. 117. — Cercospora. 



Gloeosporiuni. 



small dark-colored or black dots (acervuli). Species of 

 Gloeosporium and Melanconium are common on leaves, 

 fruits, and twigs. 



413. In the Molds (Order ]Moniliales) the conidia- 

 bearing threads emerge through the stomata of the host, 

 or grow out through the outer decaying tissues, forming 

 moldy patches or masses. Here are many common 

 parasites (e.g. species of Ramularia, Cercospora, Fusi- 

 cladium) and saprophytes (Monilia, Botrytis, etc.), some 

 of which are l)otli parasitic and saprophytic. 



Laboratory Studies. Altliou«2;h the Imperfect Fungi are 

 quite too diliicuh lor the beginner to do much with, it is well 

 that he should become somewhat familiar with their general 

 appearance; accordingly a few studies are suggested. 



