That branch of the plant sciences which considers the evolutionary relationships among plants, based on details contained in the DNA that each generation transmits to its progeny. As this has identified particular genes and in some cases revealed their function, and as biologists have acquired the ability to add, remove, and edit individual genes, it has become possible to modify plants genetically in order to confer desired properties or remove deleterious ones more quickly and much more precisely than was possible by traditional methods of plant breeding. The study of plant genetics has also allowed biologists to study the history of plant domestication and the fundamental changes that domestication brings to the plants themselves, and thereby to trace the history and geography of agriculture.