It has alternating pointed leaves and grows up to 10 cm high. The stems have many branches and are woody at the base. The flower's outer three sepals are normally small, green and insignificant, however the inner two sepals are bigger and brightly coloured blue, mauve, pink or white. The heath milkwort can be all the same colours except for white. These four possible colours account for the milkworts' Irish folk-name of 'four sisters'. In Common Milkwort, the inner sepals are usually shorter than the petals, but in the heath milkwort they are longer. The stalks of the eight stamens are joined together to form a tube, and united with this tube, one on either side, are two tiny petals. On the lower side of the flower lies the third petal; it too, is joined to the stamen tube, but it is larger, and fringed.
Text and photographs courtesy of Wikipedia.