Oscillations and movements of mimosa leaves due to electric shock∗∗

This study had been initiated while the author was a member of the College of Pharmacy. It was continued in the Department of Botany with the financial assistance of a grant of the Graduate School of the University.

Abstract

A non‐destructive radio‐frequency Q‐Meter measurement system has been applied for measuring the effects of electrical stimuli from 50 to 150 Volts d.c. to leaves of Mimosa spp. These stimuli produced rapid petiolar angular velocities of an average of 0.3 rad/sec. and a linear velocity of signal conduction in the petiole of 20 mm/sec and from the primary pulvinus to the middle of a pinna of 41 mm/sec. The expanded rotational energy of a primary petiole corresponded to 2 × 10^‐13 moles of ATP, which is much less than reported rates of dephosphorylation. However, the input of chemical equivalents of 1.1 × 10^‐10 Faradays is in good agreement. Rapid oscillations of pinnules have been observed with remarkably constant periods of time in the range from 10 to 16 seconds. Evidence is given for considering them as minute leaf electroscopes, which are periodically charged and discharged by the dissipation of the charge from the electrical shock stimulus. This charge was shown to drain off from the primary pulvinus preferentially via the mimosa leaf and r.f.‐electrode system. The wave period appears to have been determined by the ability of the tissue to transport a limited quantity of charges and by a resistance‐capacitance r.f.‐resonance between the plant and the Q‐Meter detector.

Abstracting keywords:

• Electric shock
• Mimosa leaves
• oscillations

Notes

Dept of Botany, Univ. of Minnesota, Minneapolis, Minnesota 55455, U.S.A.

This study had been initiated while the author was a member of the College of Pharmacy. It was continued in the Department of Botany with the financial assistance of a grant of the Graduate School of the University.