Written in collaboration with his son Francis, a notable botanist, this 1880 book builds on Darwin's earlier investigations into climbing plants, orchids, insectivorous plants, flower variety, and the processes of fertilisation. This detailed study of many species from seed to mature plant further develops Darwin's work on adaptation and evolution, with the aim of collating the results of individual studies into common factors applicable to plants in general. Particular emphasis is given to analysis and investigation of the process here termed circumnutation, the movement of the stem of the plant in order to direct the head in certain directions. This is seen as of paramount importance, with the conclusion that it is modification of this feature that has enabled plants to adapt and evolve so diversely. The authors also note similarities between plants and animals, such as sensitivity to touch and habit of action at certain times.