First edition of Darwin's primary work on plant fertilization. Detailing the relationship between the sexual structure of orchids and the insects that fertilize them, this was the first of three volumes that followed the publication of the Origin which contained supporting evidence for the author's theory of natural selection. Darwin concludes that plants are equal to animals in the marvels of their adaptation; for example, he observes that wind-pollinated flowers have no colours; it is only those insect-pollinated varieties that have bright coloured petals and sweet smelling nectars.