Since the 20th century, the increasing focus on the environment has drawn people's attention to the concept of ecology, bringing about Ecolinguistics, Ecoliterature, Ecosemiotics, etc. However, ecological rhetoric as a subdiscipline needs to be clarified. This essay aims to explore its origin, major strands, and future trend. We find that ecological rhetoric can be traced to Kenneth Burke's thoughts in the 1930s, and that there are four major strands --ecological composing, in situ rhetoric, transhumanism, and rhetorical ecology, of which in situ rhetoric is the most promising, justified by its philosophical foundation, transdisciplinarity, inclusiveness and operability. Philosophically, "embodiment" of in situ rhetoric originates from the body philosophy of Nietzsche, Merleau-Ponty, Lakoff and Johnson, etc.; the collaboration between rhetoric and other disciplines (anthropology, cultural studies, etc.) displays its transdisciplinarity; inclusiveness is shown in the wide range and diverse forms of research subjects; and its operability is accounted for from the feasible integration of rhetorical categories and ecological fieldwork. These four elaborated features can justify our choice of in situ rhetoric as the potential trend of ecological rhetoric.