PLANT STUDIES 
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 
FIG. 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- 
