LEAF FUNGI 165 



the iiidcToscope reveals the most varied and interesting 

 furnis. 



Vavy little apparatus is necessar}^ for the study of 

 these plants, and they would provide a most interesting 

 hobby for one who has access to a microscope. The Peri 

 sporiaccae and Microthyriaceae, the families I wish to 

 discuss, are closely related to the powdery mildews which 

 are only too well known to anyone who has a garden : 

 the rose mildew and the mildew on vines being particu- 

 larly common. They are also near relatives of the sooty 

 moulds, such as the one forming a black scabby coating 

 on orange trees which have been infested with scale or 

 other insects. But the black spots we are in search of 

 are not to be found, so far as I am aware, on cultivated 

 plants ; they are very common on native trees and shrubs, 

 and on herbaceous plants growing in humid situations. 

 The forests of the Knysna and the Zoutpansberg, the 

 wooded kloofs of the coast districts all yield a rich har- 

 vest to the collector; the only part of the country Vv^here 

 few or none have been found is the high veld, where the 

 atmosphere is too dry lo foster their growth. 



How TO Collect. 



As I have already indicated, the forest or bush is likely 

 to yield the largest number of speciments, and it will be 

 found that these fungi are most numerous on the fringes 

 of the bush, or where there is a small clearing in the 

 forest. On the lower leaves of the trees and shrubs and 

 on the herbaceous undergrowth there are numerous black 

 spots which are quite superficial and as a rule can easily 

 be scraped off the leaf with a penknife. Fig. 1 is a photo- 

 graph of a very common species, Meliola ganglifem, on 

 leaves of Ciirtisea faglnca, the Assegai wood. These may 

 be on either the upper or lower leaf surface, or less fre- 

 quently on the leaf stalks and stems; they may have a 

 velvety appearance, and when examined with the hand 

 lens show a number of erect black hairs which are 

 straight, curved or branched like a mininture forest; or 

 the fungus may only form a thin black crust. 



