Comfrey petal. Coloured scanning electron micrograph (SEM) of the petal of a comfrey or boneset (Symphytum sp. ) flower. Comfrey is an insect-pollinated plant, which bears flowers that are bright and colourful in order to attract insects. It is native to Europe and temperate Asia. It is used as a medicinal plant to alleviate the pain of coughs & sore throats. Magnification: x110 at 6x7cm size.