Biotaxonomic notes on the Rumex acetosella complex in the Netherlands

Cytological studies of the Rumex acetosella complex in the Netherlands have shown that in this country tetraploids and hexaploids occur. Such plants are referred by Löve to R. tenuifolius and R. acetosella, respectively. Diploid angiocarpous specimens belonging to R. angiocarpus have not been encountered, in contradistinction to a report by Löve. However, apart from gymnocarpous hexaploids, also angiocarpous hexaploids have been found to occur in the Netherlands. The range of distribution of these angiocarpous hexaploids corresponds with the distribution indicated by Löve for angiocarpous diploids. The results of our studies render the occurrence of the diploid R. angiocarpus in the Netherlands most unlikely. Angiocarpy can not be considered a good diagnostic character to distinguish R. angiocarpus and, accordingly, the keys to the species of Rumex belonging to the complex and the circumscription of these species by Löve and in several recent floral works are in need of revision.