»G 



FAMILIAR LESSONS IX BOTANY. 



water. By that circumstance they are never confounded 

 with algae. 



250. Fungi or mushrooms have ah-eady been fully ex- 

 plained in giving you the technical names of their several 

 parts. You were told, when learning of tissues, of the 

 effect of light upon vegetation, and that mushrooms are 

 composed of cellular tissue, and therefore grow during the 

 night, though unable to perfect spores without the agency 

 of light. We are indebted to the microscope for our 

 knowledge of several varieties of fungi. The rust upon 

 wheat, the mold upon paper-hangings, old cheese, etc. ; the 

 mildews that at some seasons so disfigure the orange-trees 

 and oleanders along our coast, are all plants, and are all 

 fungi. 



251. Lichens (Fig. 132) are those scaly wood-colored plants 

 found on trees, old buildings, fences, felled forest-trees. 



Fig. 132. 



Fig. 133. 



etc. Though generally of gray color, they are often found 

 brown, green, and yellow. The sporules are in cup-shaped 

 receptacles (Fig. 133). Sometimes these cups are upon 

 stalks, called podifa (Fig. 134) ; again these cups sit down 

 upon the tliallus, which is the leaf-like expansion of the 

 plant (Fig. 135). You will have some idea of the research 

 and industry of botanists when you hear that they have 

 described over two thousand species of this one genus. 



250. What is rust, mildew, and mold ? 

 251* What of lichens ? Their sporules ? 



