This study presents results of interdisciplinary fieldwork in Southwest China by a team of linguists and ethnobotanists. It is based on a comparative analysis of 70 common plant names in five Tibeto-Burman languages spoken in Shuiluo Valley. The discussion focuses on (a) names for locally important field crops and (b) plant names that are shared between two or more languages. We make a preliminary stratification of cognates and loanwords; we advance hypotheses about the sources of loanwords; and we assess the distribution of loanwords against the background of the existing historical and linguistic accounts of the studied languages. The observed patterns shed light on the complex migration history in the area and identify a group of plant names which may originate in a linguistic variety which was once (or still is) native to Shuiluo.