1. Nutrient limitation (mostly N or P) is a driving force in ecosystem development. Current techniques to determine the nature of nutrient limitation use laborious fertilization experiments. 2. It was hypothesized that the N:P ratio of the vegetation directly indicates the nature of nutrient limitation on a community level (N vs. P limitation). This hypothesis was tested by reviewing data on fertilization studies in a variety of European freshwater wetland ecosystems (bogs, fens, wet heathlands, dune slacks, wet grasslands). In a subset of the data (dune slacks) between-site intraspecific variation and within-site interspecific variation in nutrient content and N:P ratio was studied in five plant species. 3. A review of 40 fertilization studies reveals that an N:P ratio >16 indicates P limitation on a community level, while an N:P ratio