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Rosaceae

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 seed and have a hard fruit wall that does not split open at maturity, whereas follicles contain more than one seed and split open at maturity. Most fleshy fruits of Rosaceae are either drupes or pomes. A drupe (or stone fruit) contains one seed; the inner part of the fruit wall (the pit) is hard, and the outer fruit wall is usually fleshy. Peaches, plums, and cherries are examples of fleshy drupes, while almonds are nonfleshy. The fruits of raspberries and blackberries are clusters of many very small drupes. Pomes such as apples and pears are unusual fruits because the fleshy part does not develop from the pistil but from the hypanthium. The mature pistil containing the seeds is enclosed by the fleshy hypanthium. The fleshy part of the strawberry fruit is also not made from the pistil but from the base of the flower, which has expanded and become fleshy (accessory tissue). The fruits are achenes that are attached to the outside of the fleshy structure.

Rosaceae is very important economically. Many members of the family are important as ornamentals because of their foliage or flowers. Others are important components of diets in countries throughout the world because of

ECONOMICALLY IMPORTANT ROSACEAE SPECIES
Scientific Name	Common Name	Uses
Ornamental shrubs and trees
Chaenomeles species	Flowering quince	Flower ornamental
Cotoneaster species	Cotoneaster	Foliage and flower ornamental
Crataegus species	Hawthorn	Foliage and fruit ornamental, hedgerows
Eriobotrya japonica	Loquat	Foliage ornamental
Kerria japonica	Kerria	Flower ornamental
Malus species	Crabapple	Flower ornamental
Prunus species	Flowering cherry	Flower ornamental
Pyracantha species	Firethorn	Foliage ornamental
Rosa species	Rose	Flower ornamental
Spiraea species	Bridal wreath	Foliage and flower ornamental
Ornamental herbs
Alchemilla species	Lady's mantle	Foliage ornamental
Filipendula species	Meadowsweet	Foliage and flower ornamental
Geum species	Avens	Foliage and flower ornamental
Potentilla species	Cinquefoil	Foliage and flower ornamental
Food and wood plants
Cydonia oblonga	Quince	Fruit
Fragaria species	Strawberry	Fruit
Malus domesticus	Apple	Fruit, wood
Mespilus germanica	Medlar	Fruit
Prunus species	Cherry	Fruit
Prunus species	Plum	Fruit
Prunus amygdalus	Almond	Fruit
Prunus armeniaca	Apricot	Fruit
Prunus persica	Peach	Fruit
Prunus serotina	Wild black cherry	Wood
Pyrus communis	Pear	Fruit, wood
Rubus species	Blackberry, raspberry	Fruit

the fiber, phytochemicals, and vitamins they contain. Much of the fresh fruit eaten by people in temperate regions (apples, pears, strawberries, and cherries, for example) are members of family Rosaceae. Some members of Rosaceae are large enough to be sources of wood. The wood of wild black cherry (Prunus serotina; the largest species of Rosaceae) is a desirable furniture wood, and the wood of pear is used to make musical instruments such as recorders.