To address the ethical standing of non-human entities, we first need to define the distinctive specificity of these entities. In this chapter, we apply a pluralist approach to highlight a major ontological feature of plant life. In contrast to human beings and animals, plants are open, non self-centered subjects. In the first section, we introduce a new realist definition of the plant kingdom by considering how the plant unfolds in an open way. We argue that plant life can only be fully recognized by adopting a non-Euclidian perspective and by defining center-standing on new grounds. In the second section, we analyze how the open character of plants is modified in the process of domestication and how plant-human forms are melded by enhanced fruiting properties. We argue that the notions of plant “nutrition” and plant “reproduction” have led to radical modification of plant life now divided between an inside and an outside. In the third section, we examine what are the implications of the open character of plants at epistemological, aesthetic and ethical levels. To raise new ethical awareness, we propose to promote interdisciplinary interaction with artists in cooperative art-science-philosophical research. One issue is to work out relevant criteria and methods to explore the non-Euclidian space of plant flourishing. A second issue is to develop more participatory approaches for the design of plant-human forms in agriculture and landscape management. In conclusion, we discuss the wider implications of the philosophical concept of open being beyond plants.