Globally, crop diversity (species and varietal) has declined markedly since the mid-twentieth century. Crop diversity is especially preserved in the small holdings of Local and Indigenous communities, but together with associated practices and knowledge is often endangered. Ethiopia and Guinea are both important centres of crop diversity in Africa, including the evolution and domestication of several vegetative species. Our research in Ethiopia has focused on the major food security crop enset, or "Ethiopian false banana" (Ensete ventricosum), a tree-like perennial banana relative. Enset supports some of the densest populations in sub-Saharan Africa and is the staple for 20 million people. It is cultivated over a wide elevational range and ecological gradients, exists at very high biomass densities and has a deep cultural association with multiple ethnic groups. In West Africa, our research has focused on yams (Dioscorea cayenensis – rotundata complex) in eastern Guinea, where previously, cultivated yams have been little documented. We present and compare results on varietal diversity and uses, cultural role, consumption and cultivation, and changes in living memory. High levels of crop diversity loss were documented for both crops, but the reasons are different, highlighting the need to document agrobiodiversity and study local and crop specific drivers of change. Ethnobotany can help recover local agricultural histories and consider the dynamics of change between different crops and countries. Historic crop varieties need to be conserved insitu for future food security and resilience to climate change for both local and global foodsystems.