The family Rosaceae consists of about one hundred genera and three thousand species. It is distributed throughout the world, being especially common in North America, Europe, and Asia. Many members of the family are woody shrubs or trees. Others are perennial herbs: the stems die back at the end of each season and the root lives on to produce new stems in following seasons. The flowers of Rosaceae are distinctive because of the presence of a hypanthium, a cup-shaped structure forming the base of the flower. The sepals, petals, and stamens are attached to the edge of the hypanthium, while the pistil or pistils (which develop into the fruit or fruits) sit in the bottom of it.

One of the most conspicuous characteristics of Rosaceae is the variety of fruits produced by its species. Many Rosaceae have achenes and follicles, both of which are nonfleshy. Achenes contain one...