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P. F.  Stevens, Ph.D.

Professor of Biology, University of Missouri-St. Louis

office phone: + 1 (314) 577-0861
fax: + 1 (314) 577-0830

Missouri Botanical Garden
P.O. Box 299
St. Louis, MO 63166-0299

Ph.D., Edinburgh University, 1970
M.A., Oxford University, 1971
B.S., Oxford University, 1966
Revisionary/monographic studies Flowering plant morphology and phylogeny - see the Angiosperm Phylogeny Website Theory of character states History of natural history
Available upon request
Research Emphases Revisionary and monographic work is mostly in Clusiaceae, some Ericaceae, focussing on taxa which have part, at least, of their range in Malesia I emphasize herbarium work (including anatomical investigations, where necessary) and the careful treatment of variation that occurs sympatrically. Some of these studies may come out as conventional monographs (e.g. Mammea), others as synopses (e.g. Kayea: both with 70+ species), depending on whether floristic treatments are (Kayea) or are not (Mammea) in the offing. At the web site, set up with Hilary Davis’s help, I marry morphological, anatomical and chemical variation patterns with the most recent well-supported estimates of phylogeny. The variation is placed in a strictly hierarchical context as far as is possible. The site is updated every six months or so, and generally follows the Angiosperm Phylogeny Groups’s consensus classification, albeit a little more elaborated as the site can be kept more current both in terms of phylogenetic hypotheses and morphology. It has long seemed paradoxical to me that although morphology (in the broad sense) has been used in suggesting relationship between plants for hundreds (literally!) of years, we understand less what we are actually doing when we delimit morphological character states than is the case with DNA data. Perhaps the majority of morphological studies still have as data a set of unsubstantiated and quite possible very subjective assertions about the limits of character states that are subsequently used in phylogenetic analyses. I am currently trying to understand if different kinds (loosely defined, of course) of characters support different elements of hypotheses of phylogeny, and if so, under what conditions. There is much to do in the history of natural history, and currently (when I have time) I am trying to understand the compartmentalization and interactions of the subdisciplines that developed as the old (early eighteenth-century) natural history changed into botany, anatomy, zoology, ecology, etc.. I am looking at these subdisciplines not only as they developed into academic specialities, but also what they meant in more popular culture, and how these meanings interacted. Although not perhaps a research emphasis in the strict sense, I enjoy identifying unidentified material to family or better. This allows the material to be inserted in the herbarium and so become available for detailed study, but it is also a great way of leaning about diversity.
Selected Publications 2002. Why do we name organisms? Pointers from the past. Taxon 53 (in press). 2001. Angiosperm phylogeny website. 2000. Botanical systematics 1950-2000: change, progress, or both? Taxon 49: 635-660. 2000. On characters and character states: Do overlapping and non-overlapping variation, morphology and molecules, all yield data of the same value? Pp. 81-105 in Homology and Systematics: Coding Characters for Phylogenetic Analaysis, in R. W. Scotland & R. T. Pennington, eds. Routledge: London. 1999. Chapter 3 in W. S. Judd, C. S. Campbell, E. A. Kellogg, & P.F.S., Plant Systematics: A Phylogenetic Approach. Sinauer: Sunderland, Mass. 1998. (J. K. Jarvie & PFS.) New species and notes on Violaceae and Flacourtiaceae from Indo-Malesia. Harvard Pap. Bot. 3: 253-262. 1998. The Angiosperm Phylogeny Group (K. Bremer, M. W. Chase & PFS.) An ordinal classification for the families of flowering plants. Ann. Missouri Bot. Gard. 85: 531-553. 1997. J.D. Hooker, George Bentham, Asa Gray and Ferdinand von Mueller on species limits in theory and practice - a mid-nineteenth century debate and its repercussions. Hist. Records Australian Sci. 11: 345-370. 1997. (N. Gift & PFS.) Vagaries in the delimitation of character states - an experimental study. Syst. Biol. 46: 112-125. 1997. How to interpret botanical classifications: Suggestions from history. BioScience 47: 243-250. 1996. On phylogenies and data bases - where are the data, or are there any? Taxon 45: 94-98. 1994. The Development of Biological Classification: Antoine-Laurent de Jussieu, Nature, and the Natural System, xxiii + 616 pp. Columbia University Press: New York.