410 LESSONS WITB PLANTS 



bark of the host. There is, then, a third class of 

 these dependent plants, — the epiphytes, or those 

 which perch or grow upon other plants, without 

 obtaining food from their juices. They are only 

 squatters, not robbers. The "Spanish moss" of 

 the South, — which is really a flowering plant, — is 

 an epiphyte or air-plant, and so are many flower- 

 ing plants in southern Florida and the tropics. 

 The pupil may see epiphytes in the better green- 

 houses,' where many kinds of epiphytic orchids are 

 grown upon pieces of bark or in hanging baskets 

 without soil; he may also find stag's -horn fern 

 in some of these houses. 



518. We have been impressed with the fact of 

 the struggle for existence from a mere mathe- 

 matical calculation of the rate of propagation; 

 we have seen some of the ways in which plants 

 are able to live together because of differences or 

 divergencies in character; and we are now again 

 impressed with the stress under which plants must ■ 

 live, when we see the unusual places and habits 

 into which they are forced. 



LXXX. PLANT SOCIETIES 



519. The pupil knows that every different 

 place, — as swamp, hill, ravine, shore, — has its 



