176 STEMS 
(Fig. 151.) Many of the most notable climbers are in the trop- 
ical regions. 
Climbing stems have no more space for the display of leaves 
than prostrate stems have, because one-half of the space for leaf 
display is cut off by the support; but the climbing position is 
much better than the prostrate position for escaping the shade 
of other plants. 
One interesting feature 
of climbing plants is their 
different ways of climb- 
ing asupport. The Bean, 
Morning Glory, and Hop 
climb by twining around 
the support. They are 
called twiners. These 
plants can not climb a 
wall, for they must have 
a support which they can 
wrap about. (Fig. 152.) 
The Sweet Pea and Grape 
Vine illustrate climbing 
by means of tendrils 
which hook about the sup- 
port. Tendrils are usually 
modified leaves or stems, 
although sometimes of 
doubtful origin. (Fig. 
158.) In some _ tendril 
climbers, as in the Japan 
Ivy, the tendrils have 
swollen ends which flatten 
Fic. 151.— A Grape Vine climbing over ggainst a wall or other 
a dead Elm tree. 
supports, where they se- 
crete a mucilaginous substance by which they are able to hold 
on tenaciously. In case of the English Ivy, the plant is held 
to the wall by roots which are as efficient as tendrils. The 
Virginia Creeper climbs by means of both roots and tendrils. In 
being able to climb vertical walls of stone or brick, the Ivies 
are well adapted for wall vines for which they are much used. 
(Fig. 154.) 
