Spontaneous rapid leaf movements and action potentials in Mimosa pudica L.

Movements and action potentials of Mimosa pudica L. plants, commonly known for their sensitivity to touch, were measured using time-lapse photography and extracellular electrical potential recording methods in 4-day experiments. In intact plants, spontaneous rapid leaf movements (RLMs) were revealed. The rapid downward movement of the leaf lasted approx. 1 s and the return to the previous position took approx. 17 min. Additionally, spontaneous action potentials (SAPs) with amplitudes of 3-100 mV and half-time of approx. 15 s were observed for the first time in M. pudica. Spontaneous APs propagated basipetally or acropetally with a velocity of 3-75 cm min(-1). 36% of SAPs passing along the shoots were accompanied by RLMs. There was a delay between the appearance of SAP and RLM, indicating that SAPs may trigger the RLMs.