is stimulus found in plants
Redvine (Brunnichia ovata) tendrils coil upon contact. Thigmotropism is a directional growth movement of curvature which occurs in response to stimulus of contact. Thigmotropism is found in twining plants and tendrils. After initial contact with support due to nutation, the tendril or twiner shows less growth in the region of contact and more growth on the opposite side. As a result, they bend around the support.
For a plant organ to bend in response to a stimulus, differential growth of cells on either side of the organ is required. For example, for the stem of a plant to bend toward a light source, cells on the shaded side of the stem near the shoot tip must elongate faster than cells on the lighted side.