The One Health concept is defined by FAO as an integrated, unifying approach aiming to sustainably balance and optimize the health of people, plants, animals and ecosystems. While the concept of health has traditionally been linked to the well-being of human kind, it has more rarely been assigned to that of animals, plants or the environment. Conversely, the view that health of any ecosystem encompasses all the intersections of that in the four mentioned components, as implied by the One Health, is relatively recent but its use has spread across the scientific literature in last decades. However, the role of plants and plant’s health as a key component of the One Health concept has not been explicitly recognized yet, as compared to that of human and animal health. This presentation outlines the main mechanisms through which plant health is at the base of One Health to the point that it has been considered to be at the root of this concept. The study, manipulation, and improvement of these relationships between the health of the four components are based on Ecology, which is the unifying discipline that explains the intersections among them that occur in natural environments, whether manipulated or not.