Plum, a small tree or shrub, and its edible fruit. Many wild and cultivated species grow in temperate regions throughout the world. The plum is closely related to the cherry, apricot, and peach. The narrow or oval, toothed leaves are preceded in early spring by clusters of white or pink, five-petaled flowers. (For picture, The fruit is round and smooth-skinned, with juicy flesh enclosing a grooved pit, or stone, that contains the seeds. A plum may be red, yellow, green, or purple. (For picture, Cultivated plums are 1 to 2 ½ inches (25 to 64 mm) in diameter, and have a sweet taste; wild plums are smaller and less sweet. Certain kinds of plums that are dried are called prunes.

Several species of plum trees are native to and grow wild in North America. The American plum is widely distributed east of the Rocky Mountains. It forms dense thickets along stream banks. The tree grows about 25 feet (8 m) tall, with willowlike leaves and red or yellow fruits about three-fourths of an inch (19 mm) in diameter. The Chickasaw plum of the southeastern United States is a twiggy shrub with half-inch (13-mm) fruits. The sand plum is a bush-like variety of the Chickasaw. The beach plum, a shrub reaching about 6 feet (1.8 m) in height, grows on dunes along the northern Atlantic coast. It has purple fruit.

Plum trees cultivated in the United States are of these four principal types:

European, or Domestica, Plums are native to Europe. The purple or yellow fruits are large and meaty. European plums are the chief source of commercial prunes. The Greengage, or Reine Claude, is one of many varieties.

Damson Plums, also native to Europe, have small, purplish fruits that adhere to their pits. There are two varieties, the French and Shropshire.

Japanese Plums, originally from China, have reddish or yellow fruits. Varieties include the Formosa, Satsuma, and Shiro.

American Plums, derived from native species, often are cross-bred with Japanese varieties. The red fruits are rather small, but the trees are hardy in regions where European plums will not grow. The DeSoto is one variety.

Plum trees are attacked by scale insects and the plum curculio. Wild plum trees frequently harbor mosaic disease, which may spread to nearby orchards.

The American plum is Prunus americana; Chickasaw, P. angustifolia; sand, P. a. watsoni; beach, P. maritima; European, P. domestica; Damson, P. d. insititia; Japanese, P. salicina. All belong to the rose family, Rosaceae.