From July 1913 to September 1913, American ecologists led by Henry C. Cowles were hosts to the International Phytogeographic Excursion in America. The Excursion was a scientific tour of significant natural environments in the United States by a visiting party of the leading European botanical experts of the time.
The visiting European scientists who joined the International Phytogeographic Excursion for all or part of its route across the United States included: Heinrich and Marie Charlotte Brockmann-Jerosch (Switzerland); Ove Paulsen (Denmark); Carl Skottsberg (Sweden); Eduard Rubel (Switzerland); Karl von Tubeuf (Germany); Carl Schroeter (Switzerland); Theodoor Stomps (Netherlands); Arthur Tansley (England); Adolf Engler (Germany); and Cecil Crampton (Scotland).
While Henry Cowles was the principal organizer of the Excursion, he was assisted by a number of American botanists. These included John M. Coulter, George D. Fuller, and Victor Shelford of the University of Chicago; Frederic and Edith Clements of the University of Minnesota; Charles Bessey and Raymond Pool of the University of Nebraska; George E. Nichols of Yale University; William Setchell, Willis Jepson, and Harvey Hall of the University of California, Berkeley; and Douglas Campbell, William S. Cooper, and Le Roy Abrams of Stanford University.
Members of the party traveled between cities by rail and made tours of local environments and plant communities by automobile and on foot. The route of the Excursion was east to west, beginning in New York City on July 27. The European botanists visited the New York Botanical Garden and the Pine Barrens of New Jersey and stopped at Niagara Falls before arriving in Chicago on August 1. Three days were spent in the Lake Michigan dunes as Henry C. Cowles led his international colleagues on an exploration of the environment that had shaped his most important ecological research.
On August 9, the Excursion reached Lincoln, Nebraska, where the party toured open prairies, high plains, and sand hills under the direction of Charles Bessey. The weather was hot -- temperatures reached 108 degrees in the afternoon - but the visiting botanists were interested to see the effects of intense cultivation and grazing on prairie vegetation. Moving west, several days were devoted to examining the varied plant communities in the mountains near Colorado Springs, Colorado. After crossing the Rockies and traveling through the alkali environment of the Great Salt Lake basin, the route of the Excursion turned northward, reaching Yakima, Washington, by August 27.
In the Pacific Northwest, the itinerary of the Phytogeographic Excursion offered opportunities to study many varieties of environments, both natural and manmade -- sagebrush ranges, irrigated agriculture, conifer forests, and alpine vegetation found in the region surrounding Tacoma, Washington. One day was spent on the slopes of Mount Rainier, and a side trip included examination of local marine algae. On September 3, the Excursion traveled south to Medford, Oregon, the base for a three-day stay at Crater Lake.
September 7 brought the visiting European scientists into California. Their tour of the state included dry chaparral on Mt. Tamalpais north of San Francisco, Yosemite National Park and its Mariposa Grove of giant Sequoia sempervirens, botanical laboratories at Berkeley and Stanford, salt marshes and marine life, and coast cypress groves at Carmel.
The last leg of the Excursion offered the scientific party an overview of the Salton Sea in Southern California and a visit to the Carnegie Institution's Tucson Desert Laboratory and the nearby Santa Catalina mountains of Arizona. Before returning to New York at the end of September, 1913, members of the Excursion were also offered an optional tour of the Grand Canyon.
English botanist and ecologist Arthur Tansley prepared a summary report on the International Phytogeographic Excursion. "Certainly no member of the international party will ever forget the overwhelming impressions we received of American landscapes and vegetation, designed truly on the grand scale," he wrote. The work of American ecologists in this vast natural environment also drew his strong praise:
"In the vast field of ecology America has secured a commanding position and from the energy and spirit with which the subject is being pursued by very numerous workers and in its most varied aspects, there can be little doubt that her present pre-eminence in this branch of biology - one of the most promising of all modern developments - will be maintained."
Tansley's report was thorough in its description of plant species and ecological zones encountered on the tour. But he could not refrain from commenting on the devastating impact of commerce and industry on America's natural environments that he and his colleagues had witnessed:
"Future generations will be slow to forgive us for the wholesale and often wanton destruction that goes on at present almost unchecked by any general feeling that it is an antisocial crime, and quick to applaud the actions and to reverence the memories of those who have done something to preserve their heritage of natural beauty. . . . [H]ere and there tracts of original untouched nature can and should be preserved for the enjoyment and use of our successors, without in any way checking general and inevitable economic development. This is work which ought to be undertaken by the community, and indeed the great national and the smaller state "parks" of the west - three of which were visited by the international party - are a sign that America is awake to her responsibilities to the future in this matter."