Rediscovery of Polycnemum majus (Amaranthaceae) in Belgium due to a 152 year old herbarium specimen

In 2018 a population of Polycnemum majus was rediscovered near Rochefort (province of Namur). The species had long been considered extinct in Belgium. The label of a herbarium specimen from 1866 led to a formerly known historical site where more than a century and a half later a population is still present. The paper recounts how the species was rediscovered and describes the site and the characteristics, ecology, status and distribution of the species.