We evaluated the use of three regional Swiss floras to reconstruct spatial and temporal dynamics of 12 selected rare plant species. We found that it was possible to estimate changes in abundance and distribution of most of the 12 species during the last 75 years, and we were able to reevaluate the degree of endangerment. However, the use of existing floras for conservation purposes is limited by several factors such as collecting time and the inadequacy of locality information of older floras. As a basis for future decision-making concerning the country-wide protection of single plants, we propose the establishment of coordinated guidelines.