ANNATTO It is hard to believe that the rich golden color of cheddar cheese actually comes from a plant. This orange-yellow color, called annatto, is extracted from the seed coats of a tropical tree, Bixa orellano. The tree has heart-shaped leaves and small pink to white flowers bearing pods, which on maturing, contain hundreds of rust-colored seeds. The rust-colored resinous material surrounding the seed is the source of annatto. The chemical name for the color principle of annatto is Bixin.