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distinguished from stem tendrils by their irregular or indefinite position as well as by their mode of growth.

Fig. 169.—Tendril, to show where the coil is changed.

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 wind-storm. Usually the tendril attaches to the support by coiling about it, but the Virginia creeper and Boston ivy (Fig. 170) attach to walls by means of disks on the ends of the tendrils.

Since both ends of the tendril are fixed, when it finds a support, the coiling would tend to twist it in two. It will be found, however, that the tendril coils in different directions in different parts of its length. In Fig. 169, showing an old and stretched-out tendril, the change of direction in the coil occurred at a. In long tendrils of cucumbers and melons there may be several changes of direction.

Fig. 170.—Tendril of Boston Ivy.

Tendrils may represent either branches or leaves. In the