Tendril

Tendril, a climbing organ produced by the modification of various parts in different flowering-plants. In the vine and Virginian creeper (Ampelopsis) the flowers occasionally borne on the tendrils show them to be modified branches. The structural origin of the unbranched tendrils of the cucumbers and passion-flowers is not free from doubt; but those of the vetchling Lathyrus Aphaca as clearly represent the whole leaf (except its stipules) as those of the sweet-pea (L. odoratus) represent the terminal and some of the lateral leaflets. Darwin suggested that the twisting petio1es of Clematis and of Tropaeolum peregrinum (the "canary-creeper") represent leaves on the way towards becoming petioles. In Smilax the stipules are represented by a pair of tendrils, and in the liliaceous Gloriosa superba the apex of the leaf forms a tendril. Tendrils perform circumnutatory movements, and they are specially sensitive to contact on the inner surface of their hooked extremities. On penetrating a crevice, or on being pressed against a supporting surface, the end becomes enlarged, so as to become firmly fixed. Curcumnutation then causes spiral coiling from either end in opposite directions with a kink in the middle, thus drawing the climber nearer to its support, whilst at the same time permitting some free play in the wind.