They feed us, shelter us, cure us and clean the air that we breathe. The Roots of Civilisation takes a closer look at the plants that most of us just take for granted, but which have changed the world, for better and for worse. The Roots of Civilisation looks not only at the better known world-changers like opium, tobacco, cotton and the orchid, but also at the humbler flora that have quietly but profoundly shaped human civilisation.