The Cerasifera plums are small trees, usually upright but in some forms with spreading branches which are commonly unarmed, glabrous and brownish in color. The leaves are ovate and smaller and thinner and with more finely serrate margin than those of the Domestica plums. It blooms prolifically and bears large, white, single or paired flowers, making a most beautiful tree when in flower. The fruit is small, round, and cherry-like, from half an inch to an inch in diameter, usually red but sometimes yellow. The flesh is soft, sweetish or sub-acid and poor. The stone is turgid, smooth and pointed. The species is variable in nearly all tree-characters, and were it not surpassed by other plums for its fruit there would undoubtedly be a great number of varieties cultivated for the markets. There are, however, but few cultivated Cerasiferas, only nineteen being described in The Plums of New York. It is very generally distributed wherever plums are grown, because of the use to which it has been put as stocks for other species. For this purpose it is held in high esteem the world over. In the nurseries of New York it is now used more than any other stock and it is common to find it fruiting here and there from plants set for or used as stocks. In fact practically all the cultivated varieties have arisen as survivals of plants meant for stocks. It is almost certain that the Cerasifera, or Myrobalan, as it is universally known by horticulturists, dwarfs the cion and that it is not equally well suited to all varieties; but it does not “sprout” as badly as some other stocks, is adapted to many soils, and the young trees grow well and are rapidly budded, giving at the start a strong and vigorous orchard tree.
The Cerasifera plums are handsome trees. The foliage is a fresh and beautiful green and whether covered with a mass of flowers or loaded with red or yellow fruit these plums are as handsome as any of our cultivated fruit trees, and as desirable for ornamentals.
The hardiness, thriftiness, freedom from disease and adaptability to soils make the species desirable for hybridizing. A number of breeders of plums have made use of it with some indications of a promising future, several interesting hybrid offspring of this species being described in The Plums of New York.
The small number of varieties of Cerasifera cultivated for their fruit indicates that but little can be expected from this species by plum-growers, since so little has come from it in the shape of edible fruits, though it has been under general cultivation for over three hundred years, at least, as an ornamental and as a stock. Several valuable groups of ornamentals have arisen from Cerasifera, of which the following are most notable:—
In 1880 M. Pissard, gardener to the Shah of Persia, sent to France a purple-leaved plum which proved to be a form of Prunus cerasifera. To this plum Dippel[88] gave the name Prunus cerasifera atropurpurea, while horticulturists very generally call it Prunus pissardi. A close study of the purple-leaved plum reveals no character in which it differs from the species except in the color of foliage, flowers and fruit; the leaves are purple, as are also the calyx and peduncles of the flowers, while the fruit is a dark wine-red. These are but horticultural characters and do not seem to be of sufficient importance to establish for this plant a botanical variety. This view is strengthened by the fact that Jack[89] reports that seeds from the purple-leaved plum have produced plants which agree in all essential particulars with the species; while Kerr[90] has grown a purple-leaved plum from a variety of Prunus cerasifera.
Besides this well-known purple-leaved plum nurserymen offer Prunus pendula, a weeping form; Prunus planteriensis, bearing double white and red flowers; Prunus acutifolia, a plum with narrow, willow-like leaves; Prunus contorta, characterized by twisted, contorted foliage; Prunus elegans, Prunus gigantea, and a variety with yellow and another with variegated leaves, etc. All of these are probably horticultural varieties of Prunus cerasifera though some of them cannot be classified with surety.
Schneider[91] calls Prunus dasycarpa Ehrhart,[92] the Prunus armeniaca dasycarpa of Borkhausen,[93] a cross between Prunus cerasifera and Prunus armeniaca, one of the apricots.