Negative gravitropism of stems

This movie shows the negative gravitropic response of a sunflower seedlings after the container they were growing in was placed on its side. In less than an hour (6 frames), gravitropic curvature is underway. By the end of the second hour, the stems show a pronounced curvature. In the later stages of the response, the stems show nutational movements as they adapt to the new orientation. The images for this movie were captured every 10 min and the frames are played back at 12 frames per second.