anthocyanidin

thumb|right|200px|Molecule in 3D of the anthocyanidin cyanidin

Anthocyanidins are common plant pigments, the aglycones of anthocyanins. They are based on the flavylium cation, an oxonium ion, with various groups substituted for its hydrogen atoms. They generally change color from red through purple, blue, and bluish green as a function of pH.