The Southwestern Arboretum

The SOUTHWESTERN ARBORETUM "The Most Beautiful and Useful Garden

HIGH IN THE FOOTHILLS of the Pinal Range in Southwestern Arizona towers Picket Post Mountain, 4000 feet above the historic valley where the Pima and Apache fought for supremacy before the coming of the white man. Nearby, on a monumental butte stands Picket Post House, once the winter home of Colonel William Boyce Thompson and now a part of the vast experimental plant reservation, the Boyce Thompson Southwestern Arboretum, which he endowed during his lifetime and which under the direction of Dr. Franklin J. Crider the noted horticulturist, and Fred Gibson, the present director, has become the "most beautiful and useful garden of its kind in the world."

Like an ancient Spanish hospice, the mansion guards the long forgotten Indian trails leading into the Queen and Arnett canyons, which pass through the Arboretum from east to west, its terraces and towers commanding a panoramic view of the Superior range etched darkly against the desert horizon beyond the "Weaver's Needle" and "Apache Leap." In the fore ground, far below at the foot of the butte, lies the garden spreading over thirteen hundred acres of varied terrain; canyons, rolling hills and mesas, with a range in elevation from 2500 to 4400 feet, thus furnishing an especially favorable setting for the work of the Institution.

"The Arboretum is a plant collection representing far more than mere botanical propaga tion," said Mr. Gibson, when the writer talked with him on a recent tour of this far-reaching project.

"It was the purpose of Colonel Thompson, the founder, to develop the practical side of the work, and make the hillsides, mesas and canyons of the Southwest more productive and of greater benefit not only to that region, directly serving the ranchers, farmers and foresters, but the entire country. Here on this experimental ground we bring together and study the plants of every desert country, find out their uses and make them available to people everywhere."

Thus in a few years, a garden of rare beauty equipped with every modern facility for scientific research has grown up in the heart of this arid region and become an institution visited and utilized by people from all parts of the world; it is the first garden of its kind to serve the sub-arid regions of the earth. Along its winding drives and water courses you will find thousands of plants from distant countries blooming side by side with native growths the year around. Exotic trees and shrubs from the dry climates of Algiers, Australia and Palestine and the deserts of Central Asia, live in happy companionship with the native saguaro, paloverde, mesquite and the creosote bush. Here the fragile Mariposa lily, famed in Indian lore, nestles beneath the sturdy branches of a rambler rose; and the "Boojum Tree" like a giant inverted parsnip lifts its crown of swaying branches weirdly alien among the familiar pines and tamarisks and cacti. The utilitarian and ornamental aspects of all the plants under observation are considered scientifically, especially those that offer any promise of usefulness as food, forage for live stock, oil, rubber, tannin, dyes, medicine, perfume, firewood. shade or decorative. The plantings have been arranged to take into account, the geographical, botanical and landscape relationships. But the closest attention is given to each plant as an individual to allow it the fullest opportunity of development in its climatic and soil environment.

On the experimental tracts you will find the humble but aromatic Karoo Bush, mainstay of South African sheepmen for their forage supply which some day may cover the rangelands of Arizona and the southwest. "Our work here is far broader in scope than the name arboretum implies," said Mr. Gibson. "While we confine most of our activities to the Arboretum proper, we have secured additionalexperimental tracts in adjacent localities which provide an even wider variety of soil and climate. Through the cooperation of the Federal Forest Service, we have several such areas located in the heavily wooded Pinal Mountain range, between the elevations of 4500 and 7500 feet. In this way we are able to study plant acclimatization and adaptability from almost every part of the world."

of its Kind in the World"

"The farmers and ranchers in the Southwest are greatly interested in our experiments with forage plants," he went on. "The Karoo Bush appears to be one of the most promising forage plants for this region. The sheepmen of South Africa who depend upon it for their main forage supply, claim that it produces the best wool and a superior quality of mutton. We find in growing it here, that the plant is drouth resistant and also can flourish in very low temperatures; the roots being active at a temperature of 32 degrees. We have found that many of the plants have survived in Prescott, more than a mile above sea-level and on one of our experimental tracts between Superior and Miami at an elevation of 4500 feet. It grows faster and is hardier under all sub-arid climatic conditions than alfalfa, and compares favorably in its nourishing qualities for fodder, containing only two and a half per cent protein, while alfalfa contains about 15 per cent. Sheep relish the Karoo Bush and rabbits and other small animals will eat all but the roots. The Karoo is certainly one of our most promising aliens.."

BY FRANCES FISHER DUBUC

"Other forage plants have been tested and distributed to individual farmers. In someplants which the stock raisers consider less desirable."

Entering the main gates of the Arboretum from U. S. highway 60, about 60 miles east of Phoenix, and three miles from the picturesque little mining town of Superior, at a turn in the driveway you come upon the greenhouses and the administration building. These are built of native rough stone and house the offices, the laboratories, herbarium and seed and photographic departments. When the work of developing the Arboretum started some two decades ago under Dr. Crider, there were no improvements in the deep, arid valley. A few acres had been farmed by pioneer homesteaders and Apache Indians who lived among the cliffs along the canyons. In 1925 stone residences picturesquely conforming to the beauty of the natural setting were built for the director and his staff. Adjoining these is a commodious guest house for visitors who come from outside the state.

An irrigation system was installed with Queen Creek as the source of water supply. As this stream does not produce a constant surface flow, a well 45 feet deep was dug beside the Creek, and connected by a tunnel 125 feet long under the stream bed which catches the underground water. The entire excavation was made through solid rock and it was found necessary to blast through the top of the tunnel to allow the entrance of seepage water.

A reservoir of 3,680,000 gallons capacity was constructed in a hollow 300 yards distant, and the water lifted over a rock ledge by centrifugal pumps. Four inch underground pipe mains were laid to conduct the irrigation water by gravity to the cultivated areas.

The Arboretum is located within the boundaries of the Crook National Forest, which made it necessary to acquire much of the land from the Federal government. It was incorporated under a special act of the Arizona legislature, as at the time of organization, the state did not provide for the formation of non-profit scientific research corporations.

In cases we find that when plants are distributed under control of the United States Forest Service or other agencies, like the Soil Conservation Service and local county agents, that they are grown with more care as to the amount of grazing allowed and there are better results with some of these forage plants.

"Among the grasses which we first tested and are now being successfully distributed and grown over large parts of the state, through these agencies, are the Cape Grass, Wilman Grass, Giant Panic Bristle Grass, Oryzopsis miliacea and Eragrostis chloromelas.

"Of the shrubby plants, the Karoo Bush and several salt bushes have been the best. Anyone of these plants if given wide enough distribution and time to show its value would be a worthy fulfillment of Colonel Thompson's desire to serve this region," he added. "There is the Bunch Grass which is entirely adaptable to Arizona soil, another African growth, Also the coarse Siberian Grass which grows like tiny sticks of bamboo. There are many others we are constantly experimenting with, shrubs and larger bushes, and some of these will eventually supplement or even supersede native forage The development and progress of the “Great Southwest” centers around two major industries, mining and agriculture, including livestock and forestry, farming and forage crops. Mineralogists claim that eventually the min-erals in the hills and mountains will be ex-hausted and plant resources must become ulti mately, the base for the perpetuation of civilization in the southwest section of the country.

In the region, the plant-grower, using the term in its widest application to include all forms of agriculture-contends with problems arising directly from climatic and soil condi tions, unlike those of the Eastern States or other countries of high rainfall and greater humidity. Throughout the 500,000 square miles of the Southwest, water is the limiting factor as every one knows, the measure of agricultural develop ment. Farms, forests and ranches depend en tirely upon the amount of water supply and The “water efficiency” of plants selected for cultivation. For plants differ greatly in their moisture requirements; for example, the cotton-wood and the mesquite, or alfalfa and cotton. The Arboretum helps to solve many of these problems by studying the improvement and preservation of native and foreign plants with the purpose of making them more useful to every phase of agricultural development.

“An important part of our work here at the Arboretum is the constant search for drought-resistant varieties and the selection and breed-ing of new species requiring practically no moisture,” Mr. Gibson said. “Probably more species can be grown here under normal con-ditions, than under the same conditions in all of the gardens of Eastern United States and Western Europe. We grow successfully not only the plants of the United States and dif-ferent sections of the American continent, but

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The reservation occupies almost the geo-graphical center of the region it primarily serves, the sub-arid inland section of the southwestern part of the United States. This includes Arizona, a large part of New Mexico, a section of California, Nevada and Utah, as well as parts of Texas; in all, about 500,000 square miles.

During a visit to the Arboretum when the writer was the guest of Dr. and Mrs. Crider, the long days of the southwest spring were spent in exploring the canyons and the Indian trails, searching the mesas for plant treasures and taking pictures of interesting vistas and rare growths.

In our talks, Dr. Crider referred frequently to Colonel Thompson and their many discussions regarding the proposed establishment of a permanent plant research institution in the Southwest, while the former was in charge of the Horticultural Department of the Univer-sity at Tucson.

“His ideas and plans for such an experimental laboratory and 'garden' were based upon the vast organization in Yonkers, New York, which he had already endowed and which is making a vital contribution to science,” said Dr. Crider.

“The Colonel often spoke of man's dependence upon plants and their relation to human progress, and deplored the general tendency to destroy vegetation, particularly the forests and grazing cover. Many times as we walked among the plantings, he remarked:-'Remember, we are not planting for the present only, but for generations to come.' He contended that man has made but little progress in 'subduing' the vegetable kingdom, in developing and bringing into usefulness the multitudinous forms of wild life, comparing this lack of progress with the advance that had been made along industrial lines. He believes that dry climate plants especially, had received very little attention in this respect, and visualizing their potential possibilities, he decided that the investigational study of vegetation was the field in which he desired to make his 'contri-bution,' as he modestly expressed it, to the welfare of mankind.”