How a research domain is theoretically defined or framed might influence how it is practically perceived by citizens or experts from other research domains. This can be illustrated with the definition of ‘Phytotherapy’ often defined as ‘treatment with plants or plant components’. Following recent estimates of ‘O.M.S.’ (270.000 plant species currently identified in taxonomic Botany. Pharmaceutical treatment involves digestion or physical penetration of molecules or plant components targeting physiological or neurophysiological processes. However, psychologists guiding depressed people might argue that flowers or any vegetation used to decorate gardens, houses or green space also involve ‘Phytotherapy’. Perception of green space, including park or forest landscape, can reduce mental stress therefore improving health status. Moreover, diet specialists argue that consumed fruits contain all ingredients essential for physiological and, why not, mental performance. Thus vegetable consumption could be defined as ‘Phytotherapy’ accepting vegetables form an essential part of the human diet influencing and improving health status. The question then is why those that defined ‘Phytotherapy’ made a distinction between plants consumed or digested and plants observed or perceived? Plants consumed or digested and plants observed or perceived are just acting on different parts of the human body, either via physiology (energy, metabolism) or neuron system receptors. Any plant component improving health status could thus by definition be placed under the heading ‘Phytotherapy’. Phytotherapy therefore would involve all visual stimuli lowering stress thus reducing risks of depression or mental disease, all vegetation stimuli or components acting directly on physiology, neurology or immunology, or all plants or plant substances changing external appearance to improve social interaction and integration. It does not exclude that actions of vegetation improving health are individual-specific, whatever the plant components involved. Some people might consider wildlife herbs as waste to be removed from urban green space, whereas others might consider the same wildlife herbs as essential parts of the urban landscape reducing mental stress. Some people might also be more or less allergic to one plant component, even those currently considered as treatment in pharmaceutical research. This implies that the definition of ‘Phytotherapy’ would be individual-specific. Nearly all plants may have phytotherapeutic action in at least one individual, just depending on scales of analysis and application defined.