Washington, D.C. / Professor M. Simons / Spring 2009
Heliotropism is the diurnal motion of plant parts in response to the direction of the sun. Heliotropic ﬂ owers track the sun’s motion across the sky from East to West. During the night, the ﬂowers may assume a random orientation, while at dawn they turn again towards the East where the sun rises. Just like a heliotropic ﬂ ower reacts to sun exposure the building photovoltaic panels moves from east to west durng the course of the day to harvest solar energy.