TENDRIL - CLIMBERS 109 



seek the dark places and therefore enter the chinks in 

 walls and bark. Fig. 12, the trumpet creeper, is a fa- 

 miliar example.. The true or English ivy, which is often 

 grown to cover buildings, is another instance (Fig. 162). 

 Still another is the poison ivy. Roots are distinguished 

 from stem tendrils by their irregular or indefinite posi- 

 tion as well as by their mode of growth. 



225. TENDRIL-CLIMBERS. A slender coiling part which 

 serves to hold a climbing plant to a support is known as a 



163. Tendril of Virginia creeper. The direction of the coil changes near the middle. 



tendril. The free end swings or curves until it strikes 

 some object, when it attaches itself and then coils and 

 draws the plant close to the support. The spring of the coil 

 also allows the plant to move in the wind, thereby enabling 

 the plant to maintain its hold. Slowly pull a well -ma- 

 tured tendril from its support, and note how strongly it 

 holds on. Watch the tendrils in a storm. To test the 

 movement of a free tendril, draw an ink line lengthwise 

 of it, and note that the line is now on the concave side 

 and now on the convex side. Of course this movement is 

 slow, but it is often evident in an hour or so. Usually 

 the, tendril attaches to the support by coiling about it, but 

 the Virginia creeper and Boston ivy attach to walls by 

 means of 'disks on the ends of the tendrils. 



226. Since both ends of the tendril are fixed, when it 



