The Myrtaceae are a family, the myrtle family, of dicotyledonous plants placed within the order Myrtales. Myrtle, pohutukawa, the bay rum tree, clove, guava, acca (feijoa), allspice, and eucalyptus all are members of this group. All species are woody, with essential oils, and flower parts in multiples of four or five. One notable character of the family is that the phloem is located on both sides of the xylem, not just outside as in most other plants. The leaves are evergreen, alternate to mostly opposite, simple, and usually with an entire (not toothed) margin. The flowers have a base number of five petals, though in several genera the petals are minute or absent. The stamens are usually very conspicuous, brightly coloured and numerous.