The red cabbage (Brassica oleracea var. capitata f. rubra) is a sort of cabbage. Its leaves are coloured dark red/purple. However, the plant changes its colour according to the pH value of the soil, due to a pigment called anthocyanin (flavin). On acidic soils, the leaves grow more reddish while in alkaline soil will produce rather greenish-yellow coloured cabbages. This explains the fact that the very same plant is known by different colours in various regions. Furthermore, the juice of red cabbage can be used as a home-made pH indicator, turning red in acid and blue in basic solutions. It can be found in Northern Europe, throughout the Americas, and in China.
