The species-rich natural and seminatural grasslands of East-Central Europe have long offered diverse forages and fodder species for domestic livestock. The use and perception of forage and fodder plants are influenced by various agricultural, environmental, sociocultural, technical, and political factors. In our paper, we compared four indicator sets used by traditional land users and scientists since the Enlightenment period (18th century) until the present. We analyzed 24 literature sources and field data from Poland, Hungary, and neighboring countries. We found 2 049 records related to 529 plant species and identified 47 different types of forage/fodder quality indicators. The most often used indicators in the Enlightenment science indicator sets were “nutritional value,” “livestock preference,” and “impact on livestock health”; in the early ethnographic indicator sets (late 19th, early 20th century) “impact on livestock health” and “used for curing”; while the modern rangeland indicator set focused on “nutritional value,” “impact on livestock health,” and “productivity” of plants. The indicators used by present-day traditional herders and farmers in Hungary and Romania resembled the indicators documented in the Enlightenment period. We found data for more than 130 plant species on plant-livestock interactions that have the potential to be used in nature conservation management of seminatural pastures and meadows. The data include species currently considered protected, rare, and/or threatened in the studied countries. We argue that plant ecologists, conservation biologists, and practitioners could efficiently use historical and traditional knowledge sources about wild forage and fodder species for better and more sustainable management of species-rich grasslands in Europe.