What is Nastic Movement?
When the response by a plant to a stimulus is ignored or not directed toward the stimulus, it is called a Nastic Movement.
Generally plants, their entire body, always grow in the direction of the stimulus. But in nastic movements, parts of the plant tend to behave differently, like the closing of Petals of a flower or the folding of the leaves. This behavior is called Thigmonasty
In certain cases, the petals of a flower open according to the intensity of light. The brighter the light, the petals remain open. If light fades, then the petals close. This behavior is called Photonasty.