Researchers have demonstrated how the mechanics of phototropism work in sunflowers. Much like animals, sunflowers have a circadian rhythm. That is, an inner clock that dictates their eastward movement at sunrise. It then directs the flowers to tilt westward, to capture the last of the parting sun. The experiment was based on simple premises to rule out causes. Researcher Hagop Atamian first immobilized a group of sunflowers. The paralyzed flowers were puny and weaker. Phototropism was thus a vital factor in their health. Atamian then exposed other sunflowers to continual overhead lighting in a greenhouse. Yet for the first few days, the flowers continued with their east-west swing, which suggested an internal rhythm, rather than a direct response to the sun. The inner clock of sunflowers adds to growing evidence that keep blurring the lines between animal and vegetable life.