XIII.] 



ABOUT FUNGI. 



191 



leaf, with the Peronospora mycelium ramifying among, 

 and attacking, its cells. Peronospora gangliformis 

 attacks lettuces ; P. cffusa is found on spinach ; P. 

 Schleideniana is very destructive to young onions, and 

 P. trifoiiorum attacks the lucerne crops. So that here 

 we have five species of one family preying upon and 

 destroying man's food. Puccinia graininis causes the 

 " rust " so destructive to wheat, and P. apii attacks 

 the leaves of celery. We have elsewhere alluded to the 

 evident polymorphism of this species 

 and its connection with ALcidium 

 (fig. 144). Cy stop us candidus and 

 Glczsporium concentricum are destruc- 

 tive to the cabbage tribe ; Trichobasis 



fab(Z fatal to the growth of beans. 

 The pear is attacked by R&stelia 



cancellata; the plum by Puccinia prunorum, and other 

 fruit trees suffer under the growth of various species. 

 Oidium (fig. 145) is the well-known Vine disease, 



and fig. 146 represents Erysiphe, the 



pea-blight. Many of our garden 



flowers are attacked by various 



species, among them roses, which 



suffer from at least four different 



species. Violets, anemones, orchids, 



hollyhocks, pelargoniums, sweet- 

 williams, and ferns are among the 



victims of fungi in our gardens. 



A few years ago serious fears were 



entertained by horticulturists lest 



the whole race of hollyhocks should be destroyed 



by the ravages of Puccinia malvaccarum, a species 



