A study is made of the history of the type and related concepts, from Greek Antiquity up to the present. It is demonstrated that the type-concept of eighteenth century biology was based on Leibniz's concept of substantial form, and was not related to a Platonic Idea, whilst it is now generally understood in the sense of model or norm. In the present paper, a type-concept is developed which includes ontogenetic and phylogenetic time and various evolutionary mechanisms. This type can serve (...) as a model of the evolutionary potentialities of a taxon, and as a standard of higher classification. All classifications based on the same archetype, whether typological, numerical or phylogenetic, will be comparable, although not necessarily identical. (shrink)

In plant morphology, most structures of vascular plants can easily be assigned to pre-established organ categories. However, there are also intermediate structures that do not fit those categories associated with a classical approach to morphology. To integrate the diversity of forms in the same general framework, we constructed a theoretical morphospace based on a variety of modalities where it is possible to calculate the morphological distance between plant organs. This paper gives emphasis on shoot, leaf, leaflet and trichomes while ignoring (...) the root. This will allow us to test the hypothesis that classical morphology (typology) and dynamic morphology occupy the same theoretical morphospace and the relationship between the two approaches remains a question of weighting of criteria. Our approach considers the shoot (i.e. leafy stem) as the basic morphological structural unit. A theoretical data table consisting of as many lines as there are possible combinations between different modalities of characters of a typical shoot was generated. By applying a principal components analysis (PCA) to these data it is possible to define a theoretical morphospace of shoots. Typical morphological elements (shoots, leaves, trichomes) and atypical structures (phylloclades, cladodes) including particular cases representing ‘exotic’ structures such as the epiphyllous appendages of Begonia and ‘water shoot’ and ‘leaf’ of aquatic Utricularia were placed in the morphospace. The more an organ differs from a typical shoot, the further away it will be from the barycentre of shoots. By giving a higher weight to variables used in classical typology, the different organ categories appear to be separate, as expected. If we do not make any particular arbitrary choice in terms of character weighting, as it is the case in the context of dynamic morphology, the clear separation between organs is replaced by a continuum. Contrary to typical structures, “intermediate” structures are only compatible with a dynamic morphology approach whether they are placed in the morphospace based on a ponderation compatible with typology or dynamic morphology. The difference in points of view between typology and continuum leads to a particular mode of weighting. By using an equal weighting of characters, contradictions due to the ponderation of characters are avoided, and the morphological concepts of continuum’ and ‘typology’ appear as sub-classes of ‘process’ or ‘dynamic morphology’. (shrink)

Agnes Arber (1879-1960) was a British botanist who was a leading plant morphologist during the first half of the 20th century. She also wrote on the history and philosophy of botany. I argue in this article that her philosophical work on form and on how the work of the mind and the eye relate to each other in morphological research are relevant to the science of today. Arber's unusual blend of interests - in botany, history, philosophy, and art - put (...) her in a unique position to examine issues of form. Even her unorthodox ideas on evolution can now be seen as fitting in well with discussions of natural selection as the predominant engine of evolutionary change. Arber's views also throw light on present work dealing with developmental plant genetics and with the study of protein form. I will further argue that her marginal position relative to institutional science, while it may have left her vulnerable to criticism, also made possible her deep philosophical reflections on morphology. (shrink)

I argue here that Goethe's "delicate empiricism" is not an alternative approach to science, but an approach that scientists use consistently, though they usually do not label it as such. I further contend that Goethe's views are relevant to today's science, specifically to work on the structure of macromolecules such as proteins. Using the work of Agnes Arber, a botanist and philosopher of science, I will show how her writings help to relate Goethe's work to present-day issues of cognition and (...) perception. (shrink)