FLOWERS & COLORS

Most red, blue, or purple flowers contain pigments called anthocyanins, whose colors are sensitive to pH (the acidity or basicity of an aqueous solution). As a result, when we immerse a blue flower into an acid or basic solution, its color is likely to change to red in acid condition, or to green or yellow in basic condition. In this film, to get the most dramatic effects, we immersed all flowers in saturated sodium hydroxide (NaOH) solutions and used macro lenses and a microscope to capture their glorious color transformations. (Photography: Wenting Zhu)