Figure 1.

Elongation of the leaf were continuously measured over 7 hours and shown at different time scales. Elongation of the leaf were continuously measured over one hour and shown at different time scales (A-C), and relative elongation rate for the leaf (D). The results were shown for an hour (A), a minute (B), and a few seconds (C). In (C), the straight line corresponded to a linear regression done to obtain the elongation rate. Elongation rate variation over an hour showed random fluctuations at nm spatial scales in conjunction with the monotonous macroscopic growth (D). Noise level of the system was measured with a metal plate as a sample, and the standard deviation of the fluctuations obtained with the metal plate was less than 0.1 nm mm^-1 sec^-1.