Dandelion in UV light. Coloured photograph of a dandelion (Taraxacum officinale) showing the bull's-eye pattern of absorbed and reflected ultraviolet (UV) light. These patterns are known as 'nectar guides' and help to attract pollinating insects, which can see UV light. Humans are unable to see these patterns. This image was taken using a digital camera adapted to filter and detect UV light. The resulting monochrome image was coloured on a computer. Areas that absorb UV light are coloured red. White represents areas that reflect several wavelengths of light. Other areas are coloured as seen normally. UV light is outside the visible spectrum and does not have a true colour. See image B539/972 for daylight version.