Before one attains to great sensitiveness in the appreciation of gardens, he learns to distinguish plants by their forms. This is particularly true for trees and shrubs. Each species has its own "expression," which is determined by the size that is natural to it, mode of branching, form of top, twig characters, bark characters, foliage characters, and to some extent its flower and fruit characters. It is a useful practice for one to train his eye by learning the difference in expression of the trees of different varieties of cherries or pears or apples or other fruits, if he has access to a plantation of them. The differences in cherries and pears are very marked (Figs. 34-36). He may also contrast and compare carefully the kinds of any tree or shrub of which there are two or three species in the neighbor.

31. Plant-form in cherries. - Peine Hortense.