What is "betalain"

n. A class of red and yellow indole-derived water-soluble pigments found in beets and other plants of the Caryophyllales and used commercially as coloring agents.

Betalains are a class of red and yellow indole-derived pigments found in plants of the Caryophyllales, where they replace anthocyanin pigments. Betalains also occur in some higher order fungi. They are most often noticeable in the petals of flowers, but may color the fruits, leaves, stems, and roots of plants that contain them. They include pigments such as those found in beets.