126 THE NATURE AND WOEK OF PLANTS 



the stem of the climber may coil or twine around the 

 body of the supporting plant, or it may attach itself 

 by means of roots or tendrils. 



The hop and morning-glory are examples of the 

 twiners, and the circular movement of the tips of the 

 stems is one of the factors in coiling it round the sup- 

 port. Examine one of these plants, or a bean vine, 

 and note the firmness with which it is attached. 



That plants climb by means of roots has already 

 been noticed ( 28). The most effective climbing 

 devices, however, are tendrils. These are generally 

 modified stems, branches, flower stalks, or even 

 leaves. 



Examine the tendrils of a squash, pumpkin, pas- 

 sion flower, or balsam apple (Micrampelis). They 

 will be seen to be long slender bodies arising at the 

 nodes of the stem at the bases of the leaves. Ob- 

 serve their movement in the same manner as in the 

 stems (152). The tendril appears to be curved, with 

 a hooked tip. Draw its exact outline. Now rub the 

 surface on the inner side of the curve with a pencil, 

 and look for changes in form. It curves at the place 

 touched. Take note of the time and extent of the 

 movement. If the pencil were held in place, the ten- 

 dril would coil around it. Look for instances of 



