iia 



ORGANOGRAPHY. 



Fig. 229. roots frequently form the 



entire support of the stem 

 in consequence of this de- 

 caying at its lower part. 



Epiphytes or Air -plants. 

 — In these plants none but 

 aerial roots are produced, 

 and as these never reach 

 the soil they cannot ob- 

 tain any nourishment from 

 it, but must draw their 

 food entirely from the air 

 in which they are de- 

 veloped, hence the name 

 of air -plants which is 

 applied to them. They 

 ire also called epiphytes 

 "because they commonly 

 grow upon other plants. 

 Most Orchids {fig. 230) 

 Fig. 229, The Manprove Tree (Rhizophora and Tillandsias aiford US 

 ^'"'^^'^- illustrations of epiphy- 



tical plants. The roots of such plants are commonly green, 

 and possess a true epidermis and stomata ; in such particulars, 



Fig. 230. 



Fig. 230. Orchidaceous Plants, to show their mode of growth, a, a. Aerial 

 roots, b, b. Pseudobulbs. 



therefore, aerial roots present exceptions, as already noticed, to 

 what is commonly observed in other roots. The roots of most 



