How dynamic is place-based traditional ecological knowledge (TEK)? In what ways can its generative and conservative processes allow adaption to a changed environment? How do different cultures mediate TEK of a shared place? We address these questions with an in depth study of TEK of the diverse and socio-ecologically salient genus Rhododendron among the indigenous Naxi and immigrant Nuosu Yi of Mt. Yulong, NW Yunnan, China. TEK in both cultures is rich and intimately connected to the seasonal and elevational progression of rhododendrons. Naxi and Yi knowledge of trends and drivers of change parallel those in ecological studies. Knowledge richness was connected with place (urban vs. rural dwelling and elevation of village) and the immigrant Yi had a knowledge base as rich as that of the indigenous Naxi. Both Yi and Naxi interviewees credited this knowledge equality to a combination of generative processes (Yi villages were higher in elevation and Yi livelihoods made more use of mountain resources, which enabled them to acquire knowledge of plants quickly) and conservative processes (Yi migrated from an equally diverse mountain region in which Rhododendron is also salient; its position was retained in their system of TEK, though its elements were adapted). Among rural Naxi, cultural systems (seasonal festivals and ethnotaxonomy) conserved knowledge, even while their direct use of rhododendrons decreased with changing life-ways.