The sand cherry seems to be the dwarfing stock par excellence for the plum. This sand cherry is a heterogeneous species, or as some botanists think, is three species, ranging throughout the Northern States from Maine to Colorado. The narrow leaf upright form growing about five feet tall, known as _Prunus pumila_, is found along the Atlantic coast. The broad leafed dwarfer form known as _Prunus pumila besseyi_ or _P. besseyi_, is found in the Western States. Another rarer form of more irregular growth known as _Prunus pumila cuneata_, or as _P. cuneata_, is found in the North Central States.
[Illustration: FIG. 9--UPRIGHT CORDON PLUM
All of these different forms may be used for propagating plums or peaches. The western form (_P. besseyi_) (Fig. 8) is in some respects the best, producing the dwarfest and apparently the best trees. In our experience, however, nearly all varieties of plums and peaches give a better stand of trees when budded on _P. pumila_. _Prunus cuneata_ is inferior to the others.
The eastern form, _P. pumila_, has another advantage from the standpoint of the nurseryman in that it is more easily propagated from cuttings. For the most part the western sand cherry is propagated from seed. Both forms can be propagated from layers.
Dwarf trees are managed in the nursery very much the same as standards of the same varieties. There are no special points to be observed except in the formation of the tops. Western New York nurserymen, who now grow the principal supply of dwarf apple and pear trees, have the custom of forming their nursery stock with high heads. That is, the heads are formed at a height of eighteen inches to three feet from the ground. In this matter the pattern is taken after the usual style of standard trees. This is quite wrong. Of course, some planters might like to have dwarf trees with trunks two or three feet tall, but the best form has a much shorter stem. At any rate the buyer of dwarf trees ought to be at liberty to form the head within three or four inches of the ground if he so desires. This becomes very difficult if the tree is once pruned up to a height of two or three feet.
In order that the planter may reach his own ideal perfectly in this matter, it is sometimes necessary to buy one year old trees, what the English nurserymen call maidens. This, of course, enables the tree planter to form the head wherever he desires.