Ethnobotany studies the relationships between a people and the plants of their place. In practice that means long fieldwork with named practitioners, botanical vouchering so that the species behind a local name can be identified with certainty, and a written record that keeps the community's own categories rather than replacing them with a table of species and uses.
The vouchering is the part that separates the discipline from travel writing. A plant named in an interview is collected, pressed, deposited in a herbarium and given an accession number, so that a later researcher can check what was actually being discussed. Without it a report of a medicinal plant is a rumour with a Latin name attached, and the literature contains a great deal of that.
The harder half of the method is the part that cannot be vouchered. A tradition that calls a plant a teacher, gives it a diet and learns its song is not offering a folk theory of pharmacology that the researcher may translate into one. Luis Eduardo Luna's work with the mestizo vegetalistas of the Peruvian Amazon is the standard demonstration of how to record that faithfully: the plants keep their own status in the account, and the reader is told what the practitioners hold rather than what a laboratory would make of it.
Done that way the discipline produces something neither botany nor anthropology alone can: a record in which the identification is checkable and the meaning survives.