The hormones produced by plants at the tips of roots and shoots are known as auxins. Tendrils have auxins at their tips. Auxins are sensitive to touch, thus when tendrils are coiled around support, their growth is slowed. As a result, they shift to the opposite side of the tip in search of support, with the tendril bending in that direction as the opposite side of the tendril grows more quickly than the side that is in contact with the support.