[Wilhelm Troll (1897-1978). The tradition of idealistic morphology in the German botanical sciences of the 20th century].

During the first half of the 19th century, idealistic morphology developed into an influential research program in the German biosciences. This program was based on the concept of an ideal connection existing between various living beings. The growth of Darwinian thought and its new paradigm of historical explanation supplanted the idealistic morphology. Yet in the first half of the 20th century the principles of idealistic morphology experienced a powerful revival. Wilhelm Troll (1897-1978) was one of the most significant figures in this renaissance. Guided by the ideas of J.W. von Goethe, Troll established a research program rejecting causal, functional, and phylogenetic explanations as well as the idea of evolutionary adaptation. Instead, he attempted to create a 'pure' morphology based on the descriptions of various plant species. Governed by some explicitly metaphysical presumptions, Troll based his theory on the description of the organismal Gestalt. In consequence, his theory was actually a return to the proper idealistic morphology as it was known in the early 19th century. It lead German botanical morphology to a period of methodological and epistemological return.