Physiological studies on pea tendrils

When tendrils which have been dark adapted for 3 days are mechanically stimulated, they will only coil appreciably if they are irradiated with light. A spectral response curve suggests that this is a blue light effect. Red or far red light do not modulate this response, but a high intensity flash of blue white light given before the actinic blue light blocks coiling for 30 min. The dark-adapted tendril, which has not been previously rubbed, has the ability to store the tactile sensory information for about 60 min, but loses it if it is not irradiated within 120 min after mechanical perturbation.