128 CLIMBING PLANTS. 



the object and clasp it. Then they begin to con- 

 tract into a spiral, thus dragging the stem of the 

 plant nearer to the support, and allowing other 

 tendrils to grasp it also. The twist is in one direc- 

 tion for a number of turns, and then is reversed, 

 so that the strain is not too great (Fig. 36). Be- 

 sides bringing the shoot near its support, the spiral 

 contraction is useful as rendering the tendrils elas- 

 tic. "It is this elasticity which protects both 

 branched and simple tendrils from being torn away 

 from their supports during stormy wea-ther. I 

 have more than once gone on purpose, during a 

 gale, to watch a Bryony, growing in an exposed 

 hedge, with its tendrils attached to the surround- 

 ing bushes ; and as the thick and thin branches 

 were tossed to and fro by the wind, the tendrils, 

 had they not been excessively elastic, would in- 

 stantly have been torn off and the plant thrown 

 prostrate ; but, as it was, the Bryony safely rode 

 out the gale, like a ship with two anchors down, 

 and with a long range of cable ahead to serve as 

 a spring as she surges to the storm [Fig. 36]." 1 



When a tendril finds no support, it contracts 

 into a spiral coil, and as the end is free the turns 

 are all in the same direction (Fig. 36). In this 



1 "Climbing Plants," p. 164. 



