Although the common olive (Olea europaea) looks as though it could be a member of the myrtle family, it is in fact a member of the olive family, which contains some 600 species in addition to the olive. Both families contain several well-known plants, and they have much in common with one another.
The olive tree, also known as the common olive, is in the family Oleaceae. Native to the Mediterranean, it is winter hardy in U.S. Department of Agriculture plant hardiness zones 8 through 10 and is suited to areas with mild winters and hot, dry summers. Technically a fruit tree, the olive can grow to heights of between 20 and 30 feet, and usually spreads to 15 and 25. Flowering in early summer, the olive produces 1 1/2-inch-long green fruits, ripening to black in fall.
The myrtle family is scientifically known as the Myrtaceae, and contains over 140 genera and 3,000 species of trees and shrubs from tropical and subtropical areas around the world, as well as temperate parts of Australia. Well-known members of this family include the silver dollar tree (Eucalyptus cinerea), hardy in USDA zones 8 through 11, and the scarlet bottlebrush (Callistemon citrinus), also called the crimson, red or lemon bottlebrush and hardy in USDA zones 9 through 10.
The olive family is considerably smaller than the myrtle family, its 600 species divided into only 30 genera. Leaves are simple and pinnately compound, and flowers are usually bisexual -- meaning that the male and female parts exist in the same blossom -- but are sometimes unisexual. Although they bear no similarity to olives, well-known garden plants like weeping forsythia (Forsythia suspense), native to China and hardy in USDA zones 5 through 8, are members of the olive family.
Although olives aren’t from the Myrtaceae family, both families do share several similarities. For one, they are both composed of shrubs and trees. The plants in both families have opposite leaves, which means they have a central vein down the middle of the leaf. Members of both families produce flowers, which then give way to fruit when fertilized. This fruit is most often not edible, though obviously this is not the case with the olive.