The distribution of Galeopsis ladanum in Germany based on an analysis of herbarium material is smaller than that indicated in plant atlases.

The distribution of Galeopsis ladanum in Germany and adjacent regions was determined by a revision of specimens of Galeopsis subgen. Ladanum in major Central European herbaria. This distribution was compared with that indicated in plant atlases. For the west of Germany, beyond the range of G. ladanum, plant atlases are often misleading as they indicate the presence of this species throughout two German states and Luxembourg, but no herbarium records could be found for these regions. In other federal states, herbarium material indicated a historical distribution that is not reflected in plant atlases. Some Red Data Books give wrong assessments of the degree of endangerment. Exaggerated ranges are mapped if (i) guide books are misleading, (ii) recorders are unfamiliar with the species and (iii) similar species exist.