Opening of flower and drooping of a bud are

Step-by-step solution

Nastic movements are non-directional movements in which the direction of response or movement is determined by the epinasty (greater growth on the adaxial side, e.g., the opening of flowers), hyponasty (greater growth on abaxial side e.g., closing of flowers), thigmotactic or chemonastic bending of tentacles in Drosera. Thermonastic movements occur in the opening and closing of Tulip and Crocus flowers. In epinasty opening of fern leaf and spreading of sepal and petals during the opening of the floral bud.