These vacuolar pigments are seen when the chlorophyll degrades during leaf senescence, at which time nitrogen in the leaf is transported out of the leaf for use or storage elsewhere. Anthocyanins and betalains are commonly seen in shoots of plants that have been exposed to environmental stress, such as cold shock, exposure to salt, low light intensity, and water stress. Whether this is a special ecological or physiological strategy is still unknown. The red coloration is produced most commonly by vacuolar pigments. A developing leaf, which would be a tender meal for herbivores, forms its cells cheaply before the nitrogen-rich chlorophyll is made.
Nongreen flushes are common in lowland tropical forest plants.
Nonetheless, this hypothesis is still being tested and the answer may not be as simple as once thought. In a group of succulent plants from desert regions, living stones live mostly buried in the ground and use special coloration to disguise leaves, i.e., cryptic coloration to appear like soil and stones.