94 DEPENDENT PLANTS 



from it, but which subsist chiefly on materials that they 

 secure from air-dust, rain-water and the air. These plants 

 are epiphytes (meaning "upon plants") or air-plants. 



200. Epiphytes abound in the tropics. Orchids are 

 amongst the best known examples. (Fig. 13.) The Spanish 

 moss or tillandsia of the South is another. Mosses and 

 lichens that grow on trees and fences may also be called 

 epiphytes. In the struggle for existence, the plants probably 

 have been driven to these special places in which to find 

 opportunity to grow. Plants grow where they must, not 

 where they will. 



Review. — What is an independent plant? Dependent? Give 

 examples. How are dependent plants distinguished from others in 

 looks? Define saprophyte. Parasite. Give examples. What is a 

 host? How does a parasitic fungus live on its host? What is meant by 

 plant disease? What are hyphse? What is mycelium? What are root- 

 parasites? Give examples. What is a mycorhiza? What is the relation 

 of the soil fungus to its host? What is the role or office of saprophytes 

 in nature? Are parasites ever green? Explain. What has probably 

 been the evolution of most parasites and saprophytes? What is an 

 epiphyte? Give examples. How do epiphytes live? Why may they 

 have become epiphytes? 



Note. — Usually, the most available parasite is the dodder. It is 

 common in swales from July until autumn, winding its coral-yellow 

 stems about herbs and soft-growing bushes. It is a degraded mem- 

 ber of the morning-glory family. It produces true flowers and seeds. 

 These seeds germinate the following spring. The slender young vine 

 grows from the ground for a time, but if it fails to find a host, it perishes. 

 One of the dodders is a pest in alfalfa fields. From the Ohio River 

 southward, the mistletoe is available. 



