The Lady and the Plants: Two Notions of Teleology in Agnes Arber’s Philosophy of Plants

Agnes Arber (1879-1960) was a British plant morphologist, historian of botany, and philosopher of biology. Though now largely forgotten, her work offers valuable insights into morphological as well as philosophical issues. This paper focuses on Arber's work on teleology in plants. After providing a brief overview of her life and distinct style of work, two notions of teleology are presented, which become apparent in Arber's morphological and philosophical work. The first notion, labeled final teleology, is based on Aristotle's final cause and deals with adaptation-based explanations in biology. The second is labeled formal teleology. It is grounded in the Aristotelian formal cause and deals with the inherent directiveness of developing structures and the actualization of potentialities in organisms and their parts. Whereas Arber showed a reserved and skeptical attitude towards final teleology, she was very sympathetic to formal teleology, building her general morphological framework on it. Two examples from Arber's work are then given, which illustrate how formal teleology informed her theorizing: the partial-shoot theory of the leaf, and parallelism in evolution as a counter-proposal to natural selection. Finally, Arber's teleological interpretation of plant morphology is historically contextualized and connected to recent research developments in evolutionary biology and plant morphology.