Fertilisation of Orchids
The book was his first detailed demonstration of natural selection. It explained how complex ecological relationships resulted in the co-evolution of orchids and insects. The view has been expressed that the book led directly or indirectly to all modern work on coevolution and the evolution of extreme specialisation. It influenced botanists, and revived interest in the long neglected idea that insects played a part in pollinating flowers. It supported his view that natural selection led to a  variety of forms through the important benefits achieved by cross-fertilisation. Although the general public showed less interest and sales of the book were low, it established Darwin as a leading botanist. Orchids was the first in a series of books on his investigations into plants.