[A cytotaxonomic study of Rumex. IV. The Acetosa Mill. species]

1. Karyotypes of 18 species of the sections Scutati (2), Vesicarii (2), Hastati (4), Afroacetosae (2) and Acetosa (8) of the genus Acetosa have been investigated in detail. 2. Four evolutive tendancies were distinguished i.e.: decrease of chromosome number and arm ratio, increase of chromosome length and differentiation of sex crhomosomes. These tendancies are fully expressed in the section Acetosa as compared with the others. 3. In this section, relationships between the subsections Acetosa, Insectivalves and Americanae were established especially dealing with the change of sex determination from the type XX/XY to the type XX/XY1Y2. 4. Evolutive pathways within the genus Acetosa as well as in the whole group of Rumex sensu lato are described.