Plants display nature's optofluidic machinery

If you place a houseplant next to a sunny window, you may notice the leaves bending toward the light. Plants don't have a brain, so the vast majority of movement is controlled by the interaction of light and fluid within plant cells, says Demetri Psaltis, Dean of the School of Engineering and director of the Optics Laboratory at the École Polytechnique Fédérale de Lausanne in Switzerland.