168 
A TEXTBOOK OF GENERAL BOTANY 
The climbing habit has the disadvantage that the climbers 
are likely to fall with the death and decay of the plants on 





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Fic. 167. Cross section of a portion of round 
stem of Euphorbia tirucalli (see Fig. 164) 





Note the wide cortex specialized for water stor- 
age and photosynthesis 

which they grow. Fre- 
quently they grow over 
and shade the support- 
ing plant to such an 
extent as to kill it, and 
thus are instrumental 
in bringing themselves 
to the ground. 
In order to utilize 
the strength of some 
other object a plant 
must have some means 
of attaching itself to 
its support. There are 
four general types of 
climbers: twzners, ten- 
dril climbers, root climb- 
ers, and scramblers. 
Twiners. These plants 
climb by the simple 
device of twining spi-— 
rally around a support. 
In nature such a sup- 
port would be another 
plant. When twiners 
are cultivated, a wire 
cord or slender pole is 
usually substituted for 
the supporting plant. 
The morning-glory is 
a common example of 
the twiners. 
Tendril climbers. Climbers belonging to this class are held 
up by tendrils which are either modified stems (Fig. 165) or — 
