The rare aquatic angiosperm Elatine gussonei (Elatinaceae) is more widely distributed than previously thought

•We revised the herbarium sheets of Elatine species in 12 European herbaria.•We documented previously unknown occurrences of the endangered Elatine gussonei.•E. gussonei have a high capacity for long distance dispersal by waterbirds.•We clarified the distribution of E. gussonei.•Herbaria are important resources to clarify the status of rare species.