576 A TEXTBOOK OF BOTANY [Cn. XIV 



roots, as in English Ivy (Fig. 180), or at the ends of modified 

 tendrils, as in Boston Ivy. 



B. THE HABITATS OCCUPIED B 



The horizontal branches of trees, which spread their own 

 foliage so well to the light, nfl^oppnrt^nity^for a spread of 

 foliage by other plants also. Correspondingly 7 therejoccur 

 many small plants which grow on the branches and trusts 

 loLtrees lar above the ground, esymaUy in tropical forests ; 

 and such are the typical epiphytes! The epiphytic is the 

 logical developmentoTlinlr climbing habit. The situa- 

 tion involves difficulties, viz. the seeds must reach the 

 branches and germinate there, the plant must hold securely 

 to the slender perch, the roots must acquire the needed min- 

 eral salts and water without contact with the ground. The 

 epiphytes, however, show ample fitness to all of these condi- 

 tions in adaptations which are often remarkable. Th 

 seeds are carried chiefly by birds; tha plants are firmly 

 jmjchaEed by rooto inamu^^jnto Ibhe crevices of the bar 



decavjag^bark^leaves, etc., collected by the plant; water is 

 derived frojrTthe rainfall, absorbed and stored jnjarious 

 ways, though the limitations and inconstancy of such 

 sources have evolved xerophytic f adaptations which con- 

 serve it. 



The epiphytes include members of all the great divisions of 

 plants Algae^Jkuagy ^ Vfirworf s 1 Mnss^ Ferns, and 

 various Spermatophytes. Also epiphytes occur in the water 

 upon hydrophytes, as do parasites. The principal vege- 

 tation forms are the following. 



ORCHIDACEOUS EPIPHYTES ; with storing pseudobulbs, and 

 hanging aerial roots fitted to absorb rainfall (page 254 ; Fig. 

 126). TANK EPIPHYTES; funnel-form rosettes of leaves, 

 forming a cup which holds water, as in Mchmea (Fig. 127). 

 Water reservoirs of other forms are also frequent. NEST 

 EPIPHYTES; with certain leaves so arranged as to catch 



