Sun light is required for photosynthesis. However, it is also a limiting factor for photosynthesis. Leaves get lesser light for photosynthesis when they are in shade. Therefore, the leaves or plants in shade perform lesser photosynthesis as compared to the leaves or plants kept in sunlight. In order to increase the rate of photosynthesis in such leaves in shade, by nature the leaves have more chlorophyll pigments. This increase in chlorophyll content of the leaves leads to more absorption of sunlight by the leaves, which in turn increases the rate of photosynthesis. Therefore, the leaves or plants in shade are greener than the leaves or plants kept in the sun.