The genus Calendula includes about 15 species of annual or perennial herbs in the Asteraceae family. They are native to southwestern Asia, western Europe, Macaronesia, and the Mediterranean. The most common species is Calendula officinalis, also known as pot marigold or English marigold. When used medicinally, whole dried flowers are used, as the medicinal oils are found mostly in the resinous green bases of the flower heads. It is important to use only high-quality calendula products, so the dried petals should be bright yellow or orange as an indication of quality and freshness.