Cowles, Henry Chandler

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(b. Kensington, Connecticut, 27 February 1869;

d. Chicago, Illinois, 12 September 1939), plant ecology, botany, conservation.

Cowles was one of the pioneers of the science of ecology in the United States. At the turn of the twentieth century he produced two seminal studies on plant succession and the dynamics of community change that served as both an introduction to the science and an inspirational model for a generation of newcomers to the field. He held the first chair in plant ecology at the University of Chicago, one of the first such positions anywhere, and he influenced numerous American plant and animal ecologists through his early writings, his courses, and his field excursions. He was also instrumental in the founding of the Ecological Society of America in 1915, just two years after its British counterpart, and he was active in a number of regional conservation campaigns involving the protection of wildflowers, the establishment of forest preserves, and the preservation of the Lake Michigan sand dunes.

Early Life and Career . Cowles was born in Kensington, Connecticut, a small village near the manufacturing town of New Britain. His father, Henry Martyn Cowles, a farmer whose family had been established in the area since the seventeenth century, served as a deacon of the Congregationalist Church, superintended Sunday school instruction, and held a variety of local offices. Cowles’s mother, Eliza Whittlesley, was from Ohio, although she had relatives in central Connecticut who also traced their roots back two centuries. Henry worked on the family farm and nurtured a growing interest in natural history, particularly botany. He attended New Britain High School, where he received a solid training in the classics, and he continued his classical education at Oberlin College in Ohio. Encouraged by science instructor Albert A. Wright, Cowles supplemented his studies with courses in botany, becoming proficient at plant taxonomy, and he developed a strong interest in geology. Wright had already helped secure a place for another promising Oberlin science student, Charles Chamberlain, in the graduate program of the newly reconstituted University of Chicago. Cowles followed Chamberlain to Chicago after his graduation in 1893, and the two obtained their doctorates there and remained on the Botany Department faculty for their entire careers.

Cowles, however, went to Chicago fully expecting to study geology under the formidable duo of Thomas C. Chamberlin and Rollin Salisbury, who had just come to Chicago from the University of Wisconsin. Chamberlin had been president of the University of Wisconsin when Chicago’s president, William Rainey Harper, persuaded him to come to head the new Department of Geology. He brought his colleague Salisbury with him, and the two continued their productive collaboration in Chicago, where Salisbury eventually agreed to head a newly created Geography Department.

Geographical and geological exploration, initially under federally sponsored expeditions and then in association with state geological surveys and the U.S. Geological Survey, had attracted much attention from young scientists in the last decades of the nineteenth century. John Wesley Powell’s study of the Grand Canyon provided the initial inspiration for much work on fluvial erosion patterns, culminating, just about the time that Cowles was completing his undergraduate education, in Harvard geographer William Morris Davis’s theory of cycles of erosion, that is, stages in the life cycle of a landscape (youthful, mature, old) from a condition of varied relief and high stream gradients to one of uniform level plains and low stream gradients. Chamberlin and Salisbury emphasized postglacial erosion cycles in the American Midwest, stressing the general idea, initiated by Powell and elaborated by Davis, that the process of stream erosion led to the wearing away of a surrounding landscape to its base level, a theoretical inland extension of sea level.

After a year studying this approach to geology at Chicago, Cowles left to spend the 1894–1895 academic year teaching the sciences at Gates College in Neligh, Nebraska, a short-lived, church-affiliated school. He may have left Chicago for financial reasons, but the available records are not clear on this point. He returned in the fall of 1895, with fellowship support, and resumed his studies in geology. He also began attending the lectures of John Merle Coulter, slated to head the university’s new Botany Department. Cowles soon fell under Coulter’s influence. Harper had recruited Coulter, like Chamberlin, from the ranks of college presidents. He was still president of Lake Forest College when he began lecturing at Chicago, and he had been the president of Indiana University before that. Coulter earned his scientific reputation as botanist on the Hayden expedition to the western territories in the 1870s and as a leader in the developing field of plant morphology, as well as a promoter of what was called the “new botany,” that is, an approach that emphasized laboratory research, microscopical investigations, and physiological studies, as opposed to the older emphasis on description and classification.

One of the new fields that Coulter promoted was ecology. Impressed by Danish botanist Eugenius Warming’s recently published textbook in this field, Plantesam-fund, Coulter had sections of the book translated a day in advance so that he could lecture on them. Cowles, impatient to learn more, taught himself Danish in order to read ahead in Warming’s book. From that point on, he was committed to the science of ecology. With his background in geology, Cowles sought a research topic that could link vegetation studies with studies of land forms. Fortunately for him, the perfect research site was close at hand in the extensive region of sand dunes along the Lake Michigan shore to the south and east of Chicago. Twenty years earlier Coulter had been one of the first botanists to catalog the plant species of the region, but Cowles’s interests extended to the plant societies, as Warming had called them. He completed his doctoral dissertation under Coulter in 1898, publishing it in serial form in Coulter’s Botanical Gazette the following year under the title “Ecological Relations of the Vegetation on the Sand Dunes of Lake Michigan.” Coulter hired him immediately to teach plant ecology, perhaps the first such appointment anywhere, and he remained in that position until his retirement.

Cowles followed his work on sand dune vegetation with “The Physiographic Ecology of Chicago and Vicinity,” an equally ambitious study of the plant societies of the Chicago region that included a bit more theoretical discussion concerning the nature of ecology and his approach to the field. These two works established his reputation as a leader in plant ecology, but they did not initiate a prolific program of research and writing. Cowles continued active research for several years, but he produced no more major publications. Aside from a few suggestive articles, most of them based on brief talks at scientific meetings, and a 1911 textbook, which emphasized individual plant adaptations rather than community processes, Cowles’s original contributions to ecology ended in 1901. He kept up with the field during the next two decades, but he focused his attention on teaching, which included extensive fieldwork. His classes made frequent excursions in and around the Chicago area, taking advantage of the readily accessible regional system of railways and streetcar lines. In addition, he taught field classes during most summers, which took his students from northern Michigan to the Gulf coast and from Maine to New Mexico, Colorado, and Alaska.

By all accounts Cowles was a dynamic teacher who was at his best in the field, giving impromptu lectures as he led his charges through forests, dunes, ravines, bogs, and streams. His genial personality and relaxed style, an asset for undergraduate teaching, did not lend itself as well to the supervision of graduate students, and he tended to rely more on intuitive impressions, rather than rigorous quantitative methods, in his own fieldwork. His best-known students were perhaps William S. Cooper, who went on to direct a productive program in plant ecology at the University of Minnesota, and Arthur Vestal, who established plant ecology at the University of Illinois, but Cowles also influenced Paul Sears, Burton Livingston, and Stanley Cain, among botanists, and Victor Shelford and Charles C. Adams, among zoologists, and he exerted an indirect influence on numerous American biologists, geographers, and ecologists to the middle of the twentieth century—perhaps hundreds, according to Charles Adams and George Fuller in a tribute to their former teacher.

In 1900, Cowles married Elizabeth L. Waller of Louisville, Kentucky, a former Chicago botany student. Their only child, Harriet Elizabeth, was born in 1912. Wife and daughter often accompanied Cowles on field excursions, including the extended summer field courses.

In the summer of 1911, Henry and Elizabeth traveled to England for the International Phytogeographical Excursion in the British Isles organized by plant ecologist Arthur Tansley. They were accompanied by fellow Americans Frederic and Edith Clements and a host of European botanists. Two years later Cowles returned the favor by organizing the International Phytogeographical Excursion in the United States. He planned the itinerary, with some help from Clements and others, and then escorted his European colleagues on a whirlwind tour of the country, from the New Jersey salt marshes to the Great Plains, Colorado, California, and the Pacific Northwest, with a high point being a visit to his beloved sand dunes on the shore of Lake Michigan. Besides Tansley, the party included Adolf Engler, Carl Schröter, and Edward Rübel, among others, and the excursion convinced the Europeans of the significant contributions of Americans to this rapidly developing branch of science. Two years later, Cowles, with Victor Shelford and others, helped organize the Ecological Society of America, inspired in part by Tansley’s establishment of its British equivalent in 1913.

Physiographic Plant Ecology . Cowles thought of ecology as the study of the organic processes that accompany the dynamic physiographic changes which Chamberlin and Salisbury described. Hence he chose to call his specialty “physiographic plant ecology.” His article on the Lake Michigan sand dune vegetation began as follows: “The province of ecology is to consider the mutual relations between plants and their environment. Such a study is to structural botany what dynamical geology is to structural geology.” He further noted that just as the physiographer focuses on changing topographic forms, the ecologist employs the methods of physiography and focuses on the changing flora. With this connection in mind, he decided that a most fitting subject for ecological research would be the plant communities on the shifting sands of the dunes along the southern and eastern Lake Michigan shoreline.

Succession, the process by which the composition of vegetation changes in a regular and predictable fashion— as, for example, when a plowed field is abandoned and allowed to return to prairie or forest, or when a patch of forest recovers after a wind storm, or when a pond slowly fills in—had been observed for centuries, but few researchers had studied the process in detail. On sand dunes, Cowles reasoned, substrate and vegetation interact in a most intense and direct manner, and the ecologist can follow the sequence of changes that may occur at one location over a long span of time by tracing those same changes horizontally as one proceeds inland from the shore. At the Indiana end of Lake Michigan the region of sand dunes extended some thirty miles along the shore, and older, established dunes could be found in places as distant as five miles inland. There was a striking sequence of changing vegetation, from the youngest dunes, supporting only scattered cottonwoods and dune grasses, to older dunes populated by prairie grasses, shrubs, and pines, to still older dunes, farther inland, supporting a mixed oak forest on a rich layer of humus.

Cowles carefully documented the characteristics of each successive plant society, noting local differences in soil, water, wind, and other factors. Cowles utilized Warming’s classification scheme for plant societies–xerophytic, mesophytic, hydrophytic–based upon the level of moisture available in the soil, although he later found it inadequate to account for all differences in vegetation. Warming also had alluded to a final stage in succession, an endpoint. Cowles designated this final, and relatively stable, stage as the climax, thus introducing the term that would dominate much of American plant ecology for half a century.

Studies of succession and the climax are associated more with Cowles’s contemporary Frederic E. Clements, who was a much more prolific writer and developed a strong following, first at the universities of Nebraska and Minnesota, and then at a number of research centers in the West associated with the Carnegie Institution. Clements’s work followed more closely a tradition within plant geography, initiated by Alexander von Humboldt and elaborated upon by numerous European phytogeographers in the nineteenth century, that identified whole assemblages of plants, usually called formations, with the climatic regimes in which they are found. For Clements, then, the climax was ultimately an expression of the general climate in a region; there was one climax formation associated with each region and climate, and once achieved it remained stable indefinitely. Because Cowles identified ecology closely with physiography, and since he chose to focus more at the local than the regional level, he tended to view plant societies as continually changing, along with the land forms with which they are associated.

The climax, for Cowles, was more an ideal, like the base level in physiography, than a fixed and inevitable endpoint. Just as no landscape is ever permanent, no plant society remains the same in one place for very long. Chamberlin’s work, rooted, like that of Powell and Davis, in the progressive evolutionary perspective of the late nineteenth century, viewed geological processes as proceeding in an orderly and regular fashion, as though following an inevitable pattern of development. Clements, equally influenced by the progressive evolutionary views of Herbert Spencer and others, tended to see the climax as an organic entity, a kind of superorganism, a mature stage in a process that begins with disturbance and instability and ends with internal stability and resistance to disturbance.

Although Cowles sympathized with aspects of this view, and he sometimes referred to the climax as the stable and inevitable result of a successional sequence, he did not view the climax as a superorganism, and he saw the entire process as dynamic and continually changing, a view, one might say, more in keeping with the progressive politics and social theories of his Chicago colleagues in and around the university, where he was associated with individuals and civic organizations that included urban planners, settlement house workers, and social reformers attempting to monitor and grasp the problems of a rapidly industrializing and urbanizing society.

Cowles never fully developed his ideas about plant succession; there is no mature statement of his views. In a talk titled “The Causes of Vegetative Cycles,” delivered in 1910 as the outgoing president of the Association of American Geographers, Cowles stressed the complexity of vegetation change and the continual interaction of physiographic, climatic, and biotic processes. Within large regional climatic regimes, Cowles argued, there are always smaller processes taking place that involve local responses to topography, water relations, and the contingencies of plant and animal distribution patterns. When invited to write the volume on ecology in a two-volume botany textbook coauthored with Chicago colleagues Coulter and Charles R. Barnes, Cowles sidestepped the topic of plant societies and succession entirely and focused instead on the adaptations of individual plants, and individual plant structures, to their immediate environmental conditions. This was a viewpoint inspired by the work of German botanist Gottlieb Haberlandt, whose ideas Cowles incorporated into a course on Ecological Anatomy which he had been offering at the university regularly for over a decade.

Scientific Organization, Public Service, and Conservation . Cowles was instrumental in the organization of numerous scientific societies. As a natural public speaker and genial host he was also a frequent choice to hold office. He served as president of the Ecological Society of America in 1918 and the Botanical Society of America in 1922. He helped organize the Association of American Geographers, serving as its president in 1910. He also offered his services generously to local and regional organizations. He was very active in the Illinois State Academy of Science, the Geographic Society of Chicago, and the Chicago Academy of Sciences, serving as president of the latter from 1922 to 1934.

As an ecologist and ardent field naturalist living in a region undergoing rapid urban and industrial development, he turned his attention as well to issues of conservation and preservation. He helped found the Wild Flower Preservation Society and the Prairie Club, a kind of midwestern counterpart to the Sierra Club, and he contributed to the establishment of the Illinois state park system and the Cook Country Forest Preserves, which still provide a welcome green ring around the city of Chicago. He was very active in the movement to preserve the Indiana sand dunes, testifying eloquently at the 1916 hearings held by Stephen Mather, a colleague in local conservationist organizations who had become head of the U.S. National Park Service.

Cowles also rendered his services frequently as an expert witness in legal disputes. He testified in litigation involving river pollution in Illinois, and from 1912 to 1921, as a result of a suggestion to federal attorneys by a former student, he became involved in lawsuits conducted by the U.S. Department of Justice. Many of these cases had to do with land fraud in Arkansas and Louisiana. The most complex case, settled in the U.S. Supreme Court in the early 1920s, involved a dispute between Texas and Oklahoma brought on by the discovery of oil in the bed of the Red River, which forms the border between the states. In that case Cowles was pitted indirectly against Frederic Clements, through the testimony of a Texas botanist.

In later years Cowles relegated much of the ecology teaching to his former student George Damon Fuller while he took on more administrative responsibilities. He filled in as department chair for Coulter during the latter’s absence in 1923–1924, and, following Coulter’s retirement, he assumed the chairmanship of the Botany Department from 1925 to 1928, although his official position was listed as secretary.

Cowles’s health began to fail in the late 1920s, due to the onset of Parkinson’s disease. By the 1930s, he could no longer perform his duties at the university, and he officially retired in 1934. He died in his home in Chicago on 12 September 1939. When, in the height of the Great Depression, the editors of Ecology, the journal of the Ecological Society of America, solicited monetary contributions to support a special double issue in Cowles’s honor for July 1935, over three hundred people responded, most of them adding words of praise for Cowles. The resulting issue contained several notable articles, including one by Clements on “Experimental Ecology in the Public Service” and another by Tansley on “The Use and Abuse of Vegetational Concepts and Terms,” which introduced the term ecosystem to the language of ecology.


The Henry Chandler Cowles Papers can be found at the Department of Special Collections, University of Chicago.


“Ecological Relations of the Vegetation on the Sand Dunes of Lake Michigan.” Botanical Gazette 27 (1899): 95–117, 167–202, 281–308, 361–391. Cowles’s PhD dissertation.

“The Physiographic Ecology of Chicago and Vicinity: A Study of the Origin, Development, and Classification of Plant Societies.” Botanical Gazette 31 (1901): 73–108, 145–182. Published also, with an accompanying map and minor changes to the text, as The Plant Societies of Chicago andVicinity. The Geographic Society of Chicago Bulletin, no. 2. Chicago: The Geographic Society of Chicago, 1901.

“The Causes of Vegetative Cycles.” Botanical Gazette 51 (1911): 161–183. Reprinted in Annals of the Association of American Geographers 1 (1912): 3–20.

A Textbook of Botany for Colleges and Universities, vol. 2, Ecology. New York: American Book Co., 1911. The two-volume textbook lists John M. Coulter, Charles R. Barnes, and Henry C. Cowles as authors, but Cowles was the sole author of volume 2, which focuses almost exclusively on the anatomical and physiological adaptations of individual plant structures.


Adams, Charles C., and George D. Fuller. “Henry Chandler Cowles: Physiographic Plant Ecologist.” Annals of the Association of American Geographers 30 (1940): 39–43.

“American Environmental Photographs, 1891–1936.” Images from the University of Chicago Library. Library of Congress. Available from An online collection of over 4,000 photographs taken by Cowles and his colleagues on field trips and excursions; includes images of Cowles, Clements, Tansley, and other ecologists.

Cassidy, Victor M. Henry Chandler Cowles: Pioneer Ecologist. Chicago: Kedzic Sigel Press, 2007. A biography of Cowles and a selection of his major publications.

Cittadino, Eugene. “‘A Marvelous Cosmopolitan Preserve’: The Dunes, Chicago, and the Dynamic Ecology of Henry Cowles.” Perspectives on Science 1 (1993): 320–359.

———. “Borderline Science: Expert Testimony and the Red River Boundary Dispute.” Isis 95 (2004): 183–219. Discusses Cowles’s role as expert witness in a U.S. Supreme Court case.

Cooper, William S. “Henry Chandler Cowles.” Ecology 16 (1935): 281–283. Introduction to the special issue of Ecology dedicated to Cowles.

Engel, J. Ronald. Sacred Sands: The Struggle for Community in the Indiana Dunes. Middletown, CT: Wesleyan University Press, 1983. Chapter 4, “The Birthplace of Ecology,” focuses on Cowles and his influence.

Eugene Cittadino