From Agnes Arber to New Explanatory Models for Vascular Plant Development

The year 2000 marked the 50th anniversary of the publication of Agnes Arber's (1879-1960) book, The natural philosophy of plant form (Arber, 1950). To honour this occasion, and to celebrate Dr. Arber's contributions to botany, Rolf Rutishauser and I organized this symposium 'From Agnes Arber to new explanatory models for vascular plant development' at the XVI International Botanical Congress in St. Louis, MO, USA, in August 1999. The seven papers published here are the fruits of this symposium. Although Agnes Arber made deep and important contributions to botany, in recent years her work has largely been eclipsed by the rise of phylogenetic systematics with its emphasis on reconstructing evolutionary relationships, and by new techniques that have shifted our research focus toward molecular, physiological and genetic aspects of plant development. Technical innovation in both systematics and molecular biology has been extremely rapid. With the new techniques have come an unprecedented amount of data. What is often forgotten in times like these is that our interpretation of the data is contingent on the models we bring to them. Data alone do not support or refute any theory. That they seem to favour one theory over another does not reflect the structure of the data themselves, but results from an interaction between the data and the models in whose light we interpret them. Agnes Arber's work is a powerful reminder of this fact. She constantly reminds us of the relationship between data and theory by returning again and again to the data to view them in new ways, reinterpreting them in the light of new theories. The papers in this symposium demonstrate some of the ways in which Arber's own theories and methods have been influential today. Annals of Botany was the natural choice for publication of this symposium. This journal was Dr. Arber's favourite venue for publication. She published 43 of her 218 nonbook publications (including notes and obituaries) in this journal, more than twice the number published in her second favourite vehicle, The New Phytologist (18 papers) (Arber, 1968a,b; Schmid and Arber, 1977). Most of her papers in Annals of Botany were lengthy treatments of plant anatomy and morphology. The present symposium celebrates several facets of Dr. Arber's work. Beginning this collection of papers, Schmid presents a brief account of Agnes Arber's life and summarizes some important themes in her life, including a description of her home in Cambridge where she carried