2 SO 
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 not 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 slellaris (L.) Nyb., 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. 
