In the plant world, a tendril is a thin stem or leaf with a thread-like shape that climbing plants, such as the grape vine, use for support and attachment. Ancient vines twined tendrils around trees, whereas today they grow around intricate trellis systems in the vineyard. These tendrils have the ability to perform photosynthesis. In addition to forming on other hosts, tendrils will form robust links with their own stems and leaves on the vine, as seen here. This results in a tangled or net-like shoot.
In many cases, the tendril is a flexible and modified shoot, such as a leaf or part of a leaf, that forms improperly. Tendrils are thigmotropic, which means that they are sensitive to touch; when they come in contact with a support, growth on that part of the tendril accelerates, forming the coil. Tendrils take on spring shapes, holding the vine tightly to the support. In fact, these coils can absorb energy, and are very helpful for the vine in strong winds.