Final answer:
Plant movements like nastic responses and thigmotropism are controlled by hormones such as auxins, which are distributed through the xylem and phloem.
Step-by-step explanation:
In plants, movement or growth in response to external stimuli is known as tropism. Nastic movements, such as the closing of a Venus flytrap, are non-directional responses, while thigmotropism is a directional response, such as vines wrapping around a pole.
The hormones responsible for these growth patterns are distributed throughout the plant by the vascular system, consisting of the xylem and phloem. These hormones, particularly auxins, play a key role in the plant's ability to bend stems and leaves, as they induce differential growth rates on opposite sides of the stem or tendril. Moreover, substances like jasmonic acid can also influence plant behavior, triggering tendril coiling even without a mechanical stimulus.