Worshiping the light
After 3 days of growth in darkness, the pot of corn seedlings in this movie were exposed to light from a single light bulb placed in the center of the pot just above the seedling. The plants were then imaged at 10 min intervals for about 18 hours. For the first 14 hours the seedlings appear to be worshiping the light as they maintain phototropic curvature. Since gravitropism is simultaneously affecting the seedlings, the curvature that develops is a compromise between the opposing light and gravity responses. After 14 hours, the point light source was turned off and diffuse room lighting was turned on, at which point gravitropism becomes the dominant stimulus and the seedlings quickly return to a vertical orientation. Also note that during the time of the movie, the seedlings turned green and the leaves started to expand through the coleoptile.