There is nearly always genetic variability in anything measured or observed. Different cultivars can have different optimum temperatures and they can have different rates of change below or above the optima. However, temperature is not the only factor that affects anthocyanins. So does the amount of sunlight. As well there are different anthocyanin pigments and factors such as temperature and sunshine may affect each type of pigment differently (the optima can be different and the rates of change above and below the optima can be different). Many daylily flowers contain several types of anthocyanin pigments as well as other pigments in the flavonoid pigment pathway that can change the colour of the anthocyanins. They may be affected by light and temperature with different optima and rates of change.
In the graph the maximum amount of pigment is at about the temperature at B. At the warmer than optimum temperature E there is more pigment than at the cooler than optimum temperature A. On the other hand at the cooler than optimum temperature C there is more pigment than at the warmer than optimum temperature G. The relationship between just temperature and the amount of pigment is complicated and knowledge of the optima is required.
Below are three photos of 'Bela Lugosi' taken after different lengths of time that were cool or cloudy or both, showing how different the anthocyanin pigmentation of daylily flowers can be.
'Bela Lugosi' showing patterning caused by temperature and/or sunlight interacting with the internal environment of the petals in association with veins.
