FUNGI : CLA SSI PICA TION. 



139 



spores in an ascus, places these fungi on a higher scale than the mucors, 

 saprolegnias, and their relatives, wliere the number of gonidia in a sporangium 

 is always imk-tinite. 



303. Leaf curl of the peach, black knot of the plum and cherry, ergot of 

 the rye and grasses, and many other fungi are members of the ascomycetes. 

 The majority of the lichens are ascomycetes, while a few are basidiomjxetes. 



304. Classification of the fungi. — Those who believe that the fungi repre- 

 sent a natural group of plants arrange them in three large series related to 

 each other somewhat as follows: 



The Gonidium Type or Series. The 

 number of gonidia in the sporangium 

 is indefinite and variable. It may be 

 very large or very small, or even only 

 one in a sporangium. To this series 

 belong the lower fungi; ex., mucor, 

 saprolegnia, peronospora, etc. 



The Basidium Type or Series. 

 The number of gonidia on a basi- 

 dium is limited and definite, and 

 the basidium is a characteristic 

 structure; ex. uredineae (rusts), 

 mushrooms, etc. 



The Ascus Type or Series. The 

 number of spores in an ascus is 

 limited and definite, and the ascus 

 is a characteristic structure; ex. 

 leaf curl of peach (exoascus), pow- 

 dery mildews, black knot of plum, 

 black rot of grapes, etc. 



305. Others believe that the fungi do not represent a natural group, but 

 that they have developed off &om different groups of the algse by becoming 

 parasitic. As parasites they no longer needed chlorophyll, and consequently 

 lost it. They thus derive their carbohydrates from organic material manu- 

 factured by the green plants. 



According to this view the lower fungi have developed off from the lower 

 algse (saprolegnias, mucors, peronosporas, etc., being developed off from 

 siphonaceous algas like vaucheria), and the higher fungi being developed off 

 from the higher algae (the ascomycetes perhaps from the rhodophj'-ceEe). 



