Borage flowers. Flowers of the annual herb borage or starflower (Borago officinalis). This medicinal plant contains a chemical called gamma-linolenic acid (GLA) that has been shown to inhibit tumour blood vessel growth and kill cancer cells. The oil extracted from borage is rich in GLA. Borage can also be used in a compress to treat dermatitis, a condition where the skin is inflamed or irritated. Borage leaves have also been used in salads, while the flowers are used to make a blue dye. Borage grows wild in Britain and parts of Europe.