THE NATIONAL ARBORETUM

B. Y. MORRISON.

The National Arboretum in the District of Columbia was established by Act of Congress approved March 4, 1927. Under this act the Secretary of Agriculture was authorized and directed to establish and maintain a National Arboretum for purposes of research and education concerning tree and plant life. Under authority of the act the Secretary of Agriculture has appointed an Advisory Council on the planning and development of the Arboretum. The Council at present consists of 15 members, representing national organizations, including nurserymen, garden clubs, educational institutions, and others interested in the aims of the Arboretum.

Since its beginning the responsibility for the development and administration of the Arboretum has been assigned to the Bureau of Plant Industry, Soils, and Agricultural Engineering.

When land purchases now in process are completed, the National Arboretum will occupy an area of about 410 acres located in the northeast section of the District of Columbia, bounded on the west by Bladensburg Road, on the south by M Street, on the east by the Anacostia Parkway, and somewhat irregularly on the north by R Street, Hickey Lane, and New York Avenue.

Its soils are somewhat varied and its terrain is so diversified that there can be found sloping sites with almost any desired exposure.

Originally composed of some forty-odd parcels, some of which had been farmed, it is now integrated into a single whole with the tree-covered mass of Mount Hamilton along the western border, the broad, inner, relatively flat, central portion diagonally traversed by Hickey Creek and its tree-covered banks, and on the eastern borders the steep and tree-covered slopes of Hickey Ridge, which overlooks the broad expanses of the Anacostia Parkway, with the Maryland hills in the distance.

The area is served by a system of roads that give access to all parts in case of fire, nuisance, and other emergency. These will be modified from their present purely functional design when the current studies are completed and several large areas now devoted actively to nurseries will be returned to their proper uses.

In the planning now under way, the Arboretum site will be organized and operated much as is the National Zoological Garden, or any one of the national museums. This will mean that there will be a major portion of the area open to the visiting public during all work hours, a smaller section devoted to the nursery and service areas in which the public would not be interested, and a large building to house scientific research, the laboratories, and collections of herbarium materials, all of which will be the concern of the technical staff and of visiting scientists and students only. These three divisions will be somewhat separated.

The Arboretum is not open to the general public at the present time, but students can arrange to work in the herbarium, which is now housed at the Plant Industry Station at Beltsville, Md., or by appointment in advance may see the living plant collections during working days. Since there is considerable active construction under way and there will be more construction for the next few years, it is hoped that the public will be understanding.

As in all proper arboretums, the major interest lies in plants themselves, with attention to woody plants only, be they tree or shrub, provided only that they are hardy and successfully grown in this climate. With species, natural forms and variations, as the base, the collections will be enlarged to include not only those variable forms worthy of horticultural but not taxonomic rank, but as well all clonal material of hybrid or other origin. No attempt will be made to maintain varietal collections of the cultivated fruits and nuts that are maintained better elsewhere.

Because of the somewhat restricted area available for planting, it has been decided (1) that, because the Park system of the District contains larger acreages that must be kept to native trees, the Arboretum may turn its major attention to exotics; (2) that the arrangement of flowering and other materials shall be such as to throw seasonal emphasis on different parts of the Arboretum; and (3) that the planting plans shall depend for their major success on those species known to thrive in this area, with the less beautiful and those of dubious hardiness placed in secondary relationships.

In the permanent plantings that have been established, only the large azalea collection approaches the state of effective display. This, however, is still in progress, with certain alterations contemplated in the setting of the evergreen azaleas and additions to the collections of the deciduous species.

In contrast, the collections of magnolias and hollies and that of crab apples give no suggestion of what the effects will be, even in 10 years. The flank of Hickey Ridge, sloping to the south, gives a wonderful opportunity for their display, with the evergreen hollies and the evergreen magnolias the distinctive setting for the oriental magnolias that flower before their leaves, and the dark grassy meadow at the lowest level the finest base for the spring-flowering crab apples.

For the minor beauties to be found in the collections of the Leguminosae, little need be said, save that most visitors are surprised at the diversity of the redbuds. The maple collection is equally modest in its appeal, but some day we hope will boast a small grove of Acer griseum, the Chinese species with yellow bark that peels off easily.

The conifers that thoroughly enjoy our climate are not too many, but with major emphasis laid upon the juniper, the true cedars, the pines, the hemlocks, the yews, and their close relatives, one may gloss over the firs and spruces, most of them homesick for their mountains.

Whether or not the Metasequoia glyptostroboides, recently introduced into cultivation and represented in the Arboretum by several hundred seedlings, still in a cold greenhouse, will accept an outdoor site remains to be proved, but there is evidence that the lacebark pine, named for the famous botanist-collector, Bunge, will some day give us a fine grove with its sycamore-white trunks supporting dark-green, needle-covered crowns, not to be matched elsewhere.

There will be a small valley, looking down from Hickey Ridge, covered with cryptomerias. In their earliest years they will recall some reforested slope in Japan. Two hundred years from now, the visitor will gasp at their huge trunks as the visitor to Nikko may today. Nearby a flat-topped valley will show off the cedars from Mount Atlas, the Lebanon, and North India, with a thought perhaps for Kipling as one looks at the Deodars. Beyond these another valley for the other Indian pine, dedicated to Griffiths, another indefatigable botanist-collector, with its long, drooping needles colored like those of our own white pine, largely planted over the crown of the ridge.

These are all details. To name the 600,000 sheets of herbarium specimens and the 2,000 living species and forms is a dull business and pointless, for tomorrow and each succeeding year there will be more.

What one finds or learns at this place, as in any other collection, will depend entirely upon the visitor. No one will ask or expect the impossible.

B. Y. MORRISON is head of the Division of Plant Exploration and Introduction, Bureau of Plant Industry, Soils, and Agricultural Engineering, Beltsville, and acting director of the National Arboretum.

"Trees join earth and building and sky in harmony."