Few people really understand the multitudinous species and varieties of trees, shrubs, climbers, flowering and foliage plants at the command garden architect.
There are over twenty different types of maples, just as many oaks, there are poplars in all shapes and sizes, many varieties of lilacs, and scores of spirea. There are hundreds of roses and deciduous trees that come in a variety of colors, shapes, and sizes.
With other trees, shrubs, climbers and hardy plants literally "too numerous to mention," the gardener need never want for variety of material. To know these resources and to understand the possibilities of each species and variety is to master the landscape gardener's useful alphabet. "From the artistic point of view, trees have three characteristics which may be separately studied form, texture and color."
The form of the tree is important, and since there are a variety of forms, it is worthwhile to emphasize that the chosen tree form should meet the admiration of the tree lover.
The form of trees is always distinct, creating a beautiful outline. This outline can be symestical or irregular. A true lover of trees will be able to see and appreciate these distinctions rather easily.
Trees also create many different colors. Many colors may stand out as completely different from other trees, while some color differences are more subtle. The subtle differences are exciting, as the trees are distinguishable just barely by a tiny change in tint or hue.
The creating on combinations of these hues is a careful and delicate job. The true work of an artistic mind. There is, as always, a wide difference between the good and bad combinations.
Another characteristic of trees is texture. Just as there is a huge difference between a strip of mosquito netting and a piece of sail cloth, the same principles can be applied to trees.
A plane tree differs very little in form from a Kentucky coffee tree, but there is a total difference in effect that the two trees will have on an observer! Compare a catalpa with a honey locust; a tulip tree with a willow. You can contrast the aspect of the trees! These examples show how important texture is on the overall effect you are trying to create.
The horticultural calendar has certain well-marked divisions to which anyone growing plants should be mindful of. The first essay that was ever written in the English language on the subject of ornamental gardening opened with an extreme prescription for this arrangement. There ought to be gardens for all the months of the year, in which, severally, things of beauty may be then in season."
The essay goes on to create a list of the plants seasonable to each month of the year, "for the climate of London." We may doubt whether ten or twelve classes of plants can practicably be made on this basis; but we distinguish in our own feelings with great differences between spring greens, June roses, midsummer's wealth of foliage, autumn colors and winter scenes.
Most plants will not remain beautiful for more than one or two of these seasons, thus creating a serious problem for the landscape gardener. The question remains how to intermingle the perfections of all the year to create attractiveness in each group at all times? Or shall we group together those plants suitable to each successive season?