62 



PLANT RELATIONS. 



the light without developing such structures in the stem 

 as would enable it to stand upright. 



47. The erect type.— This type seems altogether the 

 best adapted for the proper display of foliage leaves. Leaves 



. 52. Passion-flower vines climbing supports by means of tendrils, which may be 



seen more or less extended or coiled. The two types of leaves upon a single stem 

 may also be noted. 



can be sent out in all directions and carried upward to- 

 wards the light ; but it is at the expense of developing an 

 elaborate mechanical system to enable the stem to retain 

 this position. There is an interesting relation between 

 these erect bodies and zones of temperature. At high alti- 



