C. Weele, H. Jiang, K. K. Palaniappan, V. B. Ivanov, K. Palaniappan, and T. I. Baskin. A new algorithm for computational image analysis of deformable motion at high spatial and temporal resolution applied to root growth: Roughly uniform elongation in the meristem and also, after an abrupt acceleration, in the elongation zone. Plant Physiology, volume 132, issue 3, pages 1138--1148, July 2003.