Ethnobotany studies the relationship between a human community and the plants around it, combining botanical identification with fieldwork among the people who name, gather, cultivate and use those plants in medicine, food and ritual. The American botanist John William Harshberger coined the term in 1895 in a lecture to the University of Pennsylvania's Archaeological Association, proposing the systematic study of plant use among Indigenous peoples of the Americas as a discipline in its own right, standing between botany and anthropology rather than being a minor branch of either.
Ritual plant use, incense, entheogens, ceremonial foods, plants tied to a festival calendar, sits at the exact intersection ethnobotany was built to study, and the discipline is frequently the only source that connects a tradition's ritual vocabulary to a specific identified species and explains the traditional knowledge, harvesting season, preparation method, ritual role, that a bare botanical name leaves out. The atlas draws on ethnobotanical fieldwork wherever a practice names a plant whose ritual meaning depends on more than its taxonomy, particularly among living Indigenous and folk traditions whose plant knowledge is transmitted orally rather than in a written pharmacopoeia.