Cross- and self-fertilization of plants – Darwin's experiments and what we know now

Abstract

The scientific work recorded by Darwin in his book on the cross-and self-fertilization of plants is an exemplar of interesting choices, careful technique, decades of work and methodical analyses that provided a plethora of robust results. The conclusions Darwin drew from his studies are, for the most part, valid and still relevant today. They focus primarily on providing data to support Darwin's hypothesis about the nature and importance of the benefits derived from cross-fertilization, although he conceded that a few plants seem to be invariably self-fertilized. The work is also a significant forerunner for the concepts of hybrid vigour and inbreeding depression. A wealth of information relating to flowers, flowering time, pollen efficacy, the results of cross-and self-pollination, the behaviour and impact of insects, seed and seed germination and plant breeding systems is scattered throughout the book. Darwin also related this book to several others he wrote in which some of these topics are included.

Orthoptera, a new order of pollinator

“…There is, of course, some overlap between these broad themes, and some of the reviews discuss more than one of the books as a result. For example, Micheneau, Johnson & Fay (2009) in their review on orchid pollination refer to Darwin's On the origin of the species and his book on variation under domestication (1859, 1868, respectively) in addition to his book on orchid pollination (Darwin, 1862), and Owens & Miller (2009) in their review on self-versus crossfertilisation include cross references to his books on orchid pollination (1862), variation under domestication (1868) and different forms of flowers (1877). Insectivorous plants (Darwin, 1875) captured Darwin's imagination, not least because of the fact that some of these plants had 'the power of movement' (Darwin, 1880), and Chase et al (2009) refer to this in their review on carnivorous plants.…”

“…In his book (Darwin, 1876), he presented data from many meticulously performed experiments, and his results presaged the development of ideas relating to hybrid vigour and inbreeding depression. Owens & Miller (2009) review his choices of plants and provide an assessment of the relevance of his work in the 21 st century. Pickersgill (2009) reviews variation under domestication and includes a discussion of Darwin's concept of species focusing on fertility/sterility in crosses, also reflecting his interest in reproductive biology.…”

“…Darwin was remarkable in the breadth of his botanical interests; he also developed major hypotheses that have stood the test of time and been an impetus to ongoing research. In addition to his most famous treatises, notably in evolutionary biology, he laid the foundations for modern research on a range of topics including biogeography (Carlquist, 2009), physiology (including plant growth hormones and action potentials; Edwards & Moles, 2009), genetics (Pickersgill, 2009), reproductive biology (Micheneau et al, 2009;Owens & Miller, 2009;Weller, 2009) and carnivorous plants (Chase et al, 2009).…”

Darwin and the evolution of flowers

“…Although most famous for that work, Darwin had wide‐ranging interests in plants, and this was reflected in a series of review articles published in this journal on areas including carnivorous plants (Chase et al ., 2009), island plants (Carlquist, 2009), the power of movement in plants (Edwards & Moles, 2009) and plant domestication (Pickersgill, 2009). He had a particular interest in the role of flowers in reproduction and wrote books on orchid pollination, cross‐ and self‐fertilization and different forms of flowers (reviewed, respectively, by Micheneau, Johnson & Fay, 2009; Owens & Miller, 2009; Weller, 2009).…”

Celebrating Darwin, the botanist

“…In addition to his most famous treatises, notably in evolutionary biology, he laid the foundations for modern research on a range of topics including biogeography (Carlquist, 2009), physiology (including plant growth hormones and action potentials; Edwards & Moles, 2009), genetics (Pickersgill, 2009), reproductive biology (Micheneau et al. , 2009; Owens & Miller, 2009; Weller, 2009) and carnivorous plants (Chase et al. , 2009).…”