The discovery of two localities of Cornus mas in the farthest south of the Netherlands induced the authors to study the distribution of the species in Northwest Europe. They arrived at the conclusion that the species is indigenous in the Netherlands, in the southern part of the calcareous district i.e. the uttermost south of the province of Limburg. A line running diagonally through Belgium from the Straits of Dover to Maastricht; in the Netherlands from Maastricht to Aachen and in Germany from Aachen to Gottingen is considered to be the northern boundary of the species area in Western Europe.