When the work of Charles Darwin is presented in an introductory class, the primary emphases are usually his voyage aboard the H.M.S. Beagle, particularly the time he spent exploring the Galapagos Islands, and the book that eventually resulted from his thoughts that began on that voyage, On the Origin of Species (Darwin 1859). Although this book, in which he proposed that evolution occurs by the process of natural selection, is unquestionably a significant contribution to our understanding of the natural world, students are left with the impression that natural selection is the extent of Darwin's contributions to science and our understanding of nature. They never realize that he published several more books and papers on the various studies that he did at his home in Kent. Introducing students to these subsequent works provides them a broader and often different view of someone they thought they knew. Darwin's botanical studies, in particular, provide good examples of his later work. The botanical work was not only descriptive but investigative as well, supplying evidence to support the theory of natural selection. As Kohn (2005: pp. 39-40) put it, "The best, most consistent, and most enduring web of evidence that Darwin ever developed in defense of his theory was botanical."
If students in introductory classes encounter Darwin's botanical work, it is most likely the last investigations that he did on plant movements in collaboration with his son Francis (Darwin & Darwin, 1896). Their explorations of phototropism and gravitropism are generally the prelude to coverage of either plant movements or plant hormones. Often omitted are Darwin's studies on plant reproduction, especially pollination biology, and carnivorous plants (Darwin, 1862, 1900, 1986). In his books on these subjects, Darwin carefully described each of the specific plants he studied. This information is key because his experiments grew out of what he gleaned from close observations of organisms, often starting with field observations. Once he established the appearance of a specific organism in his reader's mind, he proceeded to describe his thoughts and actions as he probed that organism to discover the adaptive fitness of a particular feature. Darwin's writing models how questions are asked and answered in the sciences (see "Science as Inquiry Standards" in National Research Council, 1996). Furthermore, the areas he studied mesh well with our need to explain the basic attributes of living organisms to our students (Table 1; see "Life Science Standards" in National Research Council, 1996). Examples from Darwin's investigations with plants can increase and add variety to our collection of stories for covering these topics (Kreps Frisch & Saunders, 2008) and provide a historical perspective (see "History and Nature of Science Standards" in National Research Council, 1996). Additionally, we can emphasize the universality of these characteristics by using plant-based examples, helping us raise awareness of these often neglected organisms (Uno, 1994).
Many writers have noted that Darwin's botanical work alone even without his contribution of natural selection - would have made him a significant Victorian scientist (Heslop-Harrison, 1958; Browne, 2002). In fact, when he was elected to the French Institute, it was in the Botanical Section in recognition of his discoveries with plants, not for his theory of natural selection (F. Darwin, 1899; Heslop-Harrison, 1958; Browne, 2002). Although he often protested that he was no botanist (F. Darwin, 1899; Darwin & Barlow, 1958; Heslop-Harrison, 1958), his botanical investigations led to some of his most significant and famous discoveries, such as revealing the adaptive advantage of one species producing different forms of flowers (Darwin, 1986), predicting the pollinator of an unusual orchid (Darwin, 1862; Kritsky, 1991), and concluding that plants use what we now call "hormones" to transmit information through their bodies (Darwin & Darwin, 1896). …