The use of edible flowers in cooking is a tradition that dates back several centuries in Europe. Flowers can be added to food merely as decoration, or to give it texture, flavour and colour. Always confirm the identity of the flower and check it is edible before use. Take care that any flower used as food—wild or cultivated—has not been sprayed with poisonous chemicals. Some flowers used in cooking are roses, violets, borage, marjoram, lavender, mint, oregano, fennel, marigold and nasturtium. Add marigold and nasturtium to salads, but toss them in after the vinegar dressing or they will turn brown. Use rose petals in jellies, jams or cordials, or use lavender to flavour custards and biscuits. Saffron stamens are used to colour and flavour dishes. Frosted flowers make excellent decorations and can be made by dipping them in beaten egg white, then caster sugar.