What makes a tendril coil?« Back to Questions List

They are many kinds of plants of which the climbers and creepers are considered movable plants. While creepers are plants that spread on the ground and climbers need a support structure for their growth. The support could either be a structure, a plant or a tree. Grapes, members of squash, melon family, cucumber and sweat pea are few examples of common tendril producing plants. 

Certain vines use tendrils to climb towards the sun. Tendrils are specialized shoots, leaflets or leaves that are highly sensitive to touch. The effect of tendrils is to move the plant towards an object that it can cling to. So tendrils provide the plants a way of changing its position. As soon as it makes contact with a firm support, it secures its tight hold with a great speed. Growth on the side of origin of the tendril touching the support virtually stops but on the other side it may some 200 times as fast as normal.

 
When they form initially, they are almost straight. Then while growing it waves around. This process is called circumnutation. The direction of cirumnutation could be clockwise or counter clockwise depending on the species. The tip of the tendril is sensitive to auxin which is a growth stimulating chemical hormone. Auxin causes the tendrils to coil getting involved in the asymmetrical growth around the support.

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