Blue tansy is one of three unrelated oils that come out of the still deep blue. Like German chamomile and yarrow, the colour is chamazulene, made from a colourless precursor by the heat of distillation. The rest is camphor, pinene and bornyl acetate, so it smells sweet and fruity over a camphorous base. It carries camphor, which means it is not an oil for pregnancy or epilepsy.^[2] In lab tests it held back Fusarium, the fungus behind a disease that kills date palms.^[1]