Johann Wolfgang von Goethe, 1790

Metamorphosis of Plants (originally published as Versuch die Metamorphose der Pflanzen zu erklären)

Background: The discipline of plant morphology can be traced to the work of Johann Wolfgang von Goethe, the great German poet and philosopher. In 1790, Goethe published the seminal essay Versuch die Metamorphose der Pflanzen zu erklären, now known in English as Metamorphosis of Plants. In this work, Goethe essentially discovered the (serially) homologous nature of leaf organs in plants, from cotyledons, to photosynthetic leaves, to the petals of a flower. Although Richard Owen, the powerful British vertebrate anatomist (and staunch opponent of Charles Darwin), is generally credited with first articulating a definition of the word “homology” (in 1843), it is clear that Goethe had already arrived at a sophisticated view of homology and transformation (within an idealist morphological perspective) more than fifty years earlier.

submitted by: William (Ned) Friedman

Access to article: Goethe’s essay, Metamorphosis of Plants is still in print (in Goethe’s Botanical Writings, translated by Bertha Mueller, Ox Bow Press) and is an absolutely essential read for all plant evolutionary developmental biologists. link to Amazon.com

Edmund W. Sinnott and Samuel Kaiser, 1934

Two types of genetic control over the development of shape. Bulletin of the Torrey Botanical Club 61(1):1-7.

Background: So much depends not only on a good idea but also on how we exploit it. Edmund Sinnott in the 1920's struggled to characterize evolutionary changes in fruits in a way that would uncover the relationship between size and shape. He found a very good idea in the writings of Julian Huxley on relative growth (see J. Huxley, 1932, Problems of Relative Growth). To exploit relative growth, Sinnott used comparative biology. By making simple comparisons of changes in length and width over the course of development in fruits from different lineages, Sinnott dissected the variety of transformations that underlie evolutionary diversity and sought to probe the genetic control of those changes. Historically, Sinnott's comparative studies of relative growth are interesting because few other botanists adopted the approach for five decades - until the publication of Steven J. Gould's Ontogeny and Phylogeny in 1977, which provided an attractive introduction to heterochrony and how it could be assessed using comparisons of relative growth. Gould's concept of heterochrony sent a generation of botanists back to Sinnott's fundamental studies of developmental change in evolution.

submitted by: Larry Hufford and Enrico Coen

Access to article: in the JSTOR archives

Edward O. Guerrant, Jr.,1982.

Neotenic evolution of Delphinium nudicaule (Ranunculaceae): a hummingbird-pollinated larkspur. Evolution 36(4): 699-712.

Background: This paper was among the first studies of plants to employ the now classic formalism proposed by Alberch et al. (1979) to examine heterochronic evolution. Most Delphinium species have intricate "larkspur" type flowers that are bee pollinated. Delphinium nudicaule, however, is hummingbird pollinated and is thought to be derived from a bee pollinated ancestor. The mature flowers of D. nudicaule resemble the buds of the bee pollinated taxa and Guerrant tested the hypothesis that the flowers of D. nudicaule are paedomorphic. This paper is a "classic" both because it was a pioneering effort and because it showed how genetic changes in a seemingly simple process, such as the rate of development, can result in major morphological changes. Such changes, in turn, can produce dramatic shifts in critical life history characters such as pollination syndrome.

submitted by: Pamela K. Diggle

Access to article: in the JSTOR archives