The rare, endemic zinc violets of Central Europe originate from Viola lutea Huds.

Two endemic zinc violets of the section Melanium Ging. occur on heavy metal soils of Central Europe. The form with yellow flowers is restricted to the area between Aachen, Germany, and Liege, Belgium, whereas the blue zinc violet exclusively thrives on a very small location at Blankenrode, Germany. Both violets are currently treated as separate species. Sequences of altogether 674 bp of the ITS1-5.8S rDNA-ITS2 regions of 61 different specimens of six taxa indicated that both violets are closely related to each other and also to Viola lutea Huds. Therefore these two zinc violets are, at best, subspecies or even only varieties of V. lutea. Thus they are termed V. lutea ssp. westfalica and V. lutea ssp. calaminaria in the present manuscript. Microsporogenesis, pollen morphology and viability of the zinc violets, particularly of the blue violet of Blankenrode, are often defective due to disturbed meiosis. The population of the blue violet might not yet be stabilized genetically but can cope with the adverse effects of the heavy metal elements.