The power of observation: Eugen Warming (1918) Om Jordudløbere (‘Underground runners') and the ecology and evolution of clonal plants

Abstract

Although often overlooked, the Danish botanist Eugen Warming was one the founders of ecology as a science. He also wrote extensively on plant life forms, including an essay from 1918, Om Jordudløbere ('Underground runners'), which specifically focused on clonal plants. As was common among naturalists during the 19th century, Warming was exceptionally skillful in drawing conclusions from plain observation. The present paper examines how Warming understood and interpreted the ecology and evolution of clonal plants, and compares his insights with those emanating during the revival of research on clonal plants from the late 1970s onward. Several of the key topics in this revival were treated already by Warming, particularly clonal plants' ability of mobility by horizontal growth, the features affecting the 'splitting' of genets into independent ramets, and how clonal life forms evolve. Despite these thematic similarities, Warming's direct impact on later research was limited, with the possible exception of the concept of plant functional types. This does not preclude that Warming's insights have bearing on the current research agenda on the ecology and evolution of clonal plants. The paper ends with a brief discussion of horizontal growth as a means to extend genet lifespan, thereby providing a basis for evolution of clonal plant life form through processes acting within genets.