In this dissertation I propose an ethical framework for "meeting mosses." At first glance, mosses are a tiny type of plants that have been uncritically understood as "primitive plants," to the extent that they are defined by negation as "non-vascular plants." Hence, mosses have been considered as "primitive" relatives of "true" vascular plants. This distortion is linked to the fact that mosses have been overlooked and represented as a radical otherness in Western civilization. To critically examine this distortion of, and injustice toward mosses, I use the methodology of field environmental philosophy within the conceptual framework of biocultural ethics developed by Ricardo Rozzi. I complement these concepts with foundational philosophical work by continental philosophers Martin Buber and Immanuel Levinas, and ethnobotanist and indigenous writer Robin Wall Kimmerer, with emphasis on their discourses of meeting, "face-to-face," otherness, heterogeneity, and alterity. Collectively thinking with these philosophers, I address the possibility of genuinely "meeting mosses," valuing them as such and not merely as a primitive "relative" or "ancestor" of vascular plants. Drawing on several botanists' accounts of plant language and plant wisdom has sharpened my reading of human-moss interactions and enriched my engagement with the heterogeneity and alterity of the Western philosophical tradition. In his book Gardens: An Essay on the Human Condition, Humanist scholar Robert Pogue Harrison argues that care (for plants and life) is the human vocation. Harrison's discussion of the diversity of "gardens" helped me to clarify multi-dimensional human-moss interactions. In terms of content and structure, I organize my analysis based on two central dimensions of human-plant interactions stated in Rozzi's biocultural ethics: biophysical and cultural, particularly, symbolic-linguistic dimensions. I explore the biophysical dimension of biocultural conservation focusing on mosses in a region where they represent the most diverse and abundant type of plants, southwestern South America. In this region, I conducted fieldwork at three reserves in Chile, Senda Darwin Biological Reserve on Chiloe Island, Magallanes National Reserve, and Omora Ethnobotanical Park in the Cape Horn Biosphere Reserve, south of Tierra del Fuego. I investigate the linguistic-cultural dimension, through the scientific binomial nomenclature as well as through the traditional naming by indigenous cultures, particularly in China. Additionally, I examine the arts as an important cultural expression of interacting with mosses that inspires biocultural conservation. I examine the role that the arts play in the education and conservation programs at the Omora Ethnobotanical Park in Chile and Shenzhen Fairy Lake Botanical Garden in China, as a way to invite students and others to have direct encounters with mosses which lead to hands-on (tactile and place-based) moss conservation. I begin this study with a deliberation of the multiple injustices embedded in contemporary social-ecological-cultural dimensions of global change, and I suggest pathways towards caring for plants and the diversity of life. Caring for mosses is not a one-way human-plant-directed process. By nourishing our physical and cultural lives, we can metaphorically say that mosses "take care" of humans. Once we integrate both "caring for mosses" and being sensitive to the "mosses caring for us," then biocultural conservation moves towards a more reciprocal conviviality. In addition to collectively thinking with other humans, metaphorically I aim to think and feel with the mosses, and therefore I am transformed by them. This is the ultimate meaning of "meeting mosses."