Foxglove seed coat. Coloured scanning electron micrograph (SEM) of the testa or seed coat of a foxglove seed, Digitalis purpurea. The testa has an irregular honeycomb-like structure. The purpose of this is to trap small particles of soil so that when the seed falls to the ground it is anchored and can germinate in security without being blown away. The testa is mechanically protective and limits entry of solutes into the seed. Foxglove plants are found growing wild in Europe and the USA in woodland and on dry heaths. They are source of the drug digitalin, a heart drug. Magnification: x400 at 6x7cm size.