280 



PHARMACEUTICAL BOTANY 



cup-like many-chambered gleba. The basidiospores are imbedded 

 in a greenish fetid slime formed by a mucilaginous disintegration 

 of the substance of the hymenium. This fetid green material is 

 attractive to carrion flies which visit the plants and remove the 

 material with its embedded spores. The latter will riot germinate 

 until after passing through the alimentary canal of these flies. 



CLASS IV. FUNGI IMPERFECTI 



An assemblage of varied forms, the life histories of most of which 

 are imperfectly understood. In this group are included numerous 

 parasites which produce diseases in crop plants. 



SUBDIVISION V. LICHENS, THE LICHENS 



Lichens are variously colored, usually dry and leathery plants, 

 consisting of symbioses of algae and fungi. In each case the fungus 



. FIG. 149. A foliaceous lichen, Physica sldlaris (L.) Nyb. t growing on a rock. 

 The cup-shaped structures are the fruiting bodies (apothecia). At the left are 

 seen two very young plants. (Gager.} 



derives its food from materials manufactured by the algae and in 

 return extracts water from the substratum and shares it with the 

 algae. The association is therefore mutually beneficial. Blue- 

 green and Protococcus forms of Green Algae and Ascomycete Fungi 

 are for the most part concerned in lichen formation. 



