Another line of effort in which England is ahead of us, though still groping her way, is the art of growing climbers on living trees. Nature suggested this, for the woodbine sometimes drapes the hawthorn tree with a mantle of fragrant, purplish flowers and Clematis Flammula often adorns the hedgerows in August with myriads of white stars. The most famous case, however, is ivy and oak. And in our own woods every one has seen wild grape throwing up its strong ropes to the tops of the highest trees, and Virginia creeper mounting the tallest elms.
Whether this is the most artistic way to grow climbers, as many believe, I shall not attempt to decide, but certainly it is beset with the greatest and most interesting difficulties. If the climber is too strong for the tree it suggests a most unpleasant thought — strangulation, murder. And this result is sure to occur if wistaria or trumpet creeper are planted beneath small trees. On the other hand, delicate and high-bred climbers are likely to be starved by the roots of strong trees, so as to suggest poverty and failure.
The aesthetic dangers are also considerable. Nature does this thing sparingly and so should we. To treat a whole avenue in this style, or even a majority of the trees on a lawn, would expose us to ridicule. Again, the English sometimes make a stupid mistake in allowing ivy to grow on beech. It is a crime to let so weedy a plant as ivy kill a noble beech, but to cover the native loveliness of a beech trunk with anything at all is worse than a crime — it is a blunder. We ought never, or rarely, to obscure the fine tree architecture of birch, mountain ash, or flowering dogwood, or even such rough customers as hickory, honey locust, and sweet gum, for their ruggedness has perennial charm. Why not use climbers only on trees that have commonplace bark? One may shrink from calling oak, elm, maple, ash, poplar, and the nuts commonplace as to bark, but no one can describe their bark in such a way that people will know them by the bark alone. Such trees make a safer list with which to experiment.
The most perfect marriage I have heard of between a deciduous tree and a deciduous climber is that of wistaria and locust, for both have pinnate foliage and flowers of the pea type. If you use the white- flowered wistaria, there will be a third point in common. This combination is beautifully described by Neltje Blanchan in "The American Flower Garden".
The most famous example, however, is that of climbing roses on any kind of deciduous tree. England and California have a great advantage over the North in this respect for they can use larger and better varieties and have fewer insect enemies to contend with.
The surest combination we can have is Virginia creeper on elm, and a most appropriate one, for the leaflet of the climber has practically the same shape as that of the tree. But when you grow Virginia creeper on pine you get a contrast of leaf forms that is almost startling. And, since evergreens are usually narrow-leaved, while climbers are usually broad-leaved, we should feel our way more cautiously before training climbers upon conifers.