- Sun Exposure
Calathea lancifolia, the Rattlesnake Calathea, is a colorful member of the prayer plant family, Marantaceae. Calatheas are often called 'prayer plants' because of their unique leaf movements –– they raise and lower their leaves from day to night as a part of their circadian rhythm. This phenomenon is called nyctinasty. Plant movements are controlled by a flux of water pressure in the pulvini - nodes at the base of the leaves. Scientists theorize that these movements are meant to follow the sun and catch as much light as possible –– an essential trait for a forest-floor-dwelling plant!
"Calathea time lapse" on YouTube. You’re welcome.