According to physics it is not.
But for artists it can be an essential element, sometimes even standing out from other colors, so many consider white a color.
In some cultures white symbolizes purity and renewal; in western societies, it is a favorite color worn by brides. But in some Asian cultures it is worn when mourning.
In the end, white is neutral. It is how we see it that defines what it is. In a manner of speaking, white should have no color. After all, it is the result of combining all the visible wavelengths of light.
The flower is a Plumeria, and specific variants are national flowers of Nicaragua and Laos. It is called by many names including “melia” in Hawaii and “kalachuchi” in the Philippines. It is associated with fertility, female sexuality, and elite status in Mayan cultures. In Polynesia it can symbolize the relationship status of a woman, depending on which ear it is worn. In Bengali culture it is associated with funerals, but Hindus in Bali use it for temple offerings. It is a widely grown ornamental plant, usually in temples and open spaces in Asia.
(Musings brought about by the lens-artists challenge on colors.)