SAPROPHYTISM AND SYMBIOSIS 



329 



FIG. 236. An orchid (Cattleya sp.} growing as an epiphyte on a portion 

 of a branch of white birch. Note the aerial roots. 



FIG. 237. A thallose lichen, Physcia stellaris^ (L.) Nyb., growing on a 

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

 At the left are seen two very young plants. 



