Thigmotropism in Organs of the Bean Plant (Phaseolus vulgaris L.)

When each vegetative aerial organ of the young bean plant isunilaterally mechanically perturbed by gentle rubbing, it exhibitspositive thigmotropism. The internodes undergo only moderatethigmotropism, but leaves and petioles bend much more, especiallywhen they are rubbed on their abaxial surfaces. When the abaxialsurface of one petiole is rubbed, it bends down, but the oppositepetiole bends upward at the stem-petiole pulvinus. These observationsare interpreted in terms of the vining habit of bean plants. Bean, Phaseolus vulgaris, thigmotropism, mechanical perturbation