the color/light is not why prayer plants roll up. it's much cooler than that..all about water retention...
they use the same red and high wavelength blue as other plants for photosynthesis, which is why the leaves are open and mostly green when the sun is out ( we see what the plant reflects.. yellows and greens and low wavelength blues that it doesn't absorb to create sugars).
at night, when there is no sun for photosynthesis, the leaves roll up to prevent unnecessary water loss through evaporation. they seal themselves up, while at the same time, allow night rain and collected dew to drip to the now exposed plants roots, where it will stay, because when the leaves open to collect sunlight again, they shade the soil around the roots to further retain moisture.. cool, no?
red wavelengths are the most easily absorbed by chlorophyll which turns electromagnetic energy (sunlight) into chemical energy needed to create long carbon sugar chains. that's why red leaves are usually saved for high cost of flowers. The red on the back of the leaves is simply efficacy. these are forest floor plants that grow in very competitive environments, they know the back of their leaves are not going to produce, because they won't ever get sun and stay low to protect their roots. .. they don't waste chemicals to stock both sides of a leaf w chlorophyll...
Makes basil look profligate, right? so clever, our mother nature.
