CLIMBERS 113 



true roots, as explained in paragraph 31. These roots 

 are of adventitious origin. They grow in a horizontal di- 

 rection and enter the chinks of walls "or the furrows in the 

 bark of trees. Fig. 12, the trumpet creeper, is a familiar 

 example. The true or English ivy, which is often grown to 

 cover buildings, is another example. (Fig. 174.) Still another 



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



is the poison ivy. Roots are distinguished from stem tendrils 

 by their irregular or indefinite position as well as by their 

 mode of growth. 



237. Tendril-climbers. A slender coiling part that 

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

 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-matured tendril 

 from its support, and note how strongly it holds on. Watch 

 the tendrils in a storm. To test the movement of a free ten- 

 dril, 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 often it is 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. 

 H 



