The association between plant water stress and synthesis of red, anthocyanin pigments in
leaves has led some plant biologists to propose an osmotic function of leaf reddening.
According to this hypothesis, anthocyanins function as a solute in osmotic adjustment (OA),
contributing to depression of osmotic potential (Ψπ) and maintenance of turgor pressure
during drought-stressed conditions. Here we calculate the percent contribution of
anthocyanin to leaf Ψπ during OA in two angiosperm evergreen species, Galax urceolata …