Dandelions in UV light. Coloured photograph of dandelions (Taraxacum officinale) showing areas that absorb and reflect ultraviolet (UV) light. Patterns on the flower heads 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. Parts of the flower that absorb UV light are coloured red. Areas that reflect UV are lighter in colour. UV light is outside the visible spectrum and does not have a true colour. See image B539/975 for daylight version.