Comparison of a Melissa officinalis (Lemon Balm) flower photographed in visible light (top), ultraviolet (middle), and infrared (bottom). In visible light the flower is a uniform white colour. In ultraviolet light a darker area around the mouth of the flower is visible. This may act as a nectar guide, aiding bees (which can see ultraviolet light) to the area of the flower where the nectar and pollen are located. In infrared light the flower appears a single tone. The leaf of the plant appears brighter in infrared, having around the same brightness as the flower.