We must have, not merely a facile familiarity with plants, but we must have some fairly profound philosophy of their use. That is, we must be able to use plants as nature uses them, to found our selections and our groupings on the same fundamental laws which govern these matters in the wild and native landscape.
Many partial philosophies have been offered in this connection. Every one seems to be sound, as far as it goes. We may say, therefore, that they are all true, and for practical use we may add them all together and adopt the total. A brief review of these different ideas will be worth while here.
1. The use of native species in preference to exotics began to be urged strongly in America about 1890. Downing's theory of the natural style which had prevailed up to this time had endeavored to use the forms of the natural landscape without the native materials. This preference for native plants, however, was reinforced by many arguments, some of them very questionable, until it became a sort of fad. It was, therefore, only in part an effort to realize a more perfectly natural style of gardening.
2. Very soon, however, appeared the idea of mass planting. This seems to have been the special contribution of Frederick Law Olmsted, Sr. It represents a most substantial advance, since nature manifestly offers her plantings nearly always in large masses. The white pine, for instance, used to exist in solid unbroken forest masses hundreds of miles in extent. There used to be thousands of miles of prairie in this country covered with blue stem and bunch grass.
3. Nature's mass plantings, however, are controlled by very well settled conditions of soil and moisture. A mass planting of high-bush blue-berries or of New Jersey tea, for example, cannot be made indifferently anywhere the landscape gardener may choose. The blueberries are at home, native and natural, only in wet, springy or half-swampy land; and the New Jersey tea belongs characteristically on dry warm sandy banks. So our mass plantings, if they are to be true to the pattern of nature, must be placed with strict reference to soil and drainage conditions. This part of planting theory seems to have been set forth first and most clearly by Dr. Engler and Dr. Peters, respectively curator and planting foreman of the new Botanic garden of Berlin.
4. Another discovery of still more recent date calls to our aid that branch of botanical science known as ecology. It is readily observed that very few species of plants exist in nature alone. Practically every one associates habitually with certain other species. Thus they form set clubs or societies. And these friendly associations, based upon similarity of tastes and complementary habits of growth, should not be broken up. If we as landscape gardeners desire to preserve the whole aspect of nature, with all its forms intact, we will keep all plants in their proper social groupings.
For example, if we wish to use the gray birch, or squaw birch, to give a good naturalistic dress to some dry hillside, we will not leave it alone, but will use its whole society, the roll of which is somewhat as follows:
Squaw Birch, Gray Birch, JBetula populifoUa. Dwarf Savin, Dwarf Jumper, Juniperus communis.
Black Huckleberry, Gaylussaeia baccata* Sweet Fern, Myrica asplenifolia. Sumach, Rhus glabra and copallina.
Or if we have a wide stretch of barren sandy plain in Massachusetts, we will probably adopt the pitch pine flora, which is characteristic of such land. Its main features are as follows:
Pitch Pine, Pinus rigida. Scrub Oak, Quercus prinoides. Black Scrub Oak, Quercus ilicifoUa. Poverty Grass, Andropogon scoparius.
This ecological principle is the one most clearly elucidated by Willy Lange in his important work, "Die Garten-Gestaltung der Neuzeit".
Looking at the landscape from these different points of view, we gradually gain familiarity with its various forms. We learn to know the shape of the mountains, the forms of the trees, the slope of the terraces on the river banks. If we have within us any spiritual nature we learn at the same time something of the spirit of the landscape. This is obviously something much harder to define or describe. I cannot say to every man, lo, here is the spirit of the woods! or look now at the water where you shall behold the naked spirit of the lake.
Nevertheless there is a spirit of the woods and a spirit of the lake, and the spiritually minded person will certainly discern them. Even the dullest man has so much of the divine essence in him that he cannot wholly escape it. He may look on with the cow at the same fields and views, and though she gets her dinner from them he will get something more and different.
It is plain, furthermore, that this spiritual or emotional product of the landscape takes a specific quality from its physical form. The emotions communicated to the human heart from the ocean are not the same as those given by the brook. Our spirits are moved in one way by the pine forest and in a very different way by the prairies. The bank of blue blossoming lupines means one thing to us and the thundering waterfall means quite another. Yet these spiritual, emotional products can hardly be described aside from the physical forms and phenomena through which they are expressed. So poor are we in the nomenclature of the spirit.
This poverty of language, sad as it is, is no new matter, and it need not detain us now if we only understand that the absence of words does not mean a lack of facts. The spiritual portion of the world is still there, just as truly as the physical portion. Probably it is more powerful, more significant and much longer lived.
Before men became civilized into their present infidelity and materialism, our landscape was inhabited by wild Indians—the "savage" aborigines. These simple citizens lived much nearer to nature than we do and understood her a great deal better. It is a curious fact that their thought of nature was an extravagant spiritualism, almost as extreme, though never as crude, as our modern materialism. But there is every reason to suppose that they were nearer right than we are.