1. BIOSYSTEMATIC STUDIES OF THE RUMEX ACETOSELLACOMPLEX. I. ANGIOCARPY AND CHROMOSOME NUMBERS IN FRANCE
- Author
-
J. C. M. Den Nijs
- Subjects
geography.geographical_feature_category ,Rumex acetosella ,biology ,Forestry ,Plant Science ,Polyploid complex ,Massif ,biology.organism_classification ,Taxon ,Geography ,Distribution pattern ,Ethnology ,Rumex ,Random population - Abstract
SUMMARY As a sequel to biotaxonomic studies in Belgium, about 110 random population samples of Rumex acetosella L. s.l. from a large part of France were studied. Representatives of this polyploid complex were of common occurrence everywhere except in areas with a subsoil rich in lime. Angiocarpy is wide-spread, but gymnocarpy was only recorded from the French Alps. In contrast to the situation in Belgium, no correlation between the incidence of angiocarpy and a more fertile kind of soil could be established. Diploids (2n = 14) were found in the SE: Massif Central, Montagne Noire, Massif du Maure, and Massif du Mercantour in the Alpes Maritimes (altogether 36 populations); tetraploids (2n = 28, 23 populations recorded) are almost exclusively encountered in the Pyrenees and in the NE part of the Massif Central; and hexaploids (2n = 42, in 32 populations) appeared to be scattered over the remainder of the area studied, with a certain amount of sympatric overlap with the areas of the diploid and of the tetraploid chromosomal races in the Massif Central. In the zones of overlap an appreciable number of hybrids between 2n and 4n, and between 4n and 6n plants were encountered (in 11 populations). By far the large majority of the plants bear angiocarpous fruits irrespective of the level of ploidy, so that the alleged coupling between angiocarpy and diploidy (in the pertaining literature regarded as “R. angiocarpus Murb.”, with 2n = 14) must be rejected. In the Alpes Maritimes gymnocarpous diploids were found, which may be considered to represent a more primitive taxon among the aggregate. As far as can be ascertained, the distribution pattern of populations of the R. acetosella aggregate is, generally speaking, characteristic of a complex species differentiated during and after the last Ice Ages. In the discussion attention is paid to the possible causes underlying the differences in the distributional patterns (such as vegetative reproduction at higher ploidy levels). In order to obtain a more complete picture of the complex the investigations are being pursued. RESUME Comme suite aux recherches biotaxinomiques faites en Belgique, approximativement 110 echantillons des populations du Rumex acetosella L. s.l., provenantes d'une grande partie de la France, ont ete etudies. Representants de cet agglomerat polyploide etaient partout d'une presence frequente, a l'exception de regions avec un sous-sol calcifere. La forme angiocarpe se presente tres frequemment, tandis que la forme gymnocarpe ne se trouve que dans les Alpes Maritimes. Contraire a la situation en Belgique, la correlation entre l'incidence d'angiocarpie et un sol plus fertile n'a pas ete demontree. Des plantes diploides (2n = 14) ont ete trouvees dans le Sud-Est: le Massif Central, la Montagne Noire, le Massif du Maure et le Massif du Mercantour dans les Alpes Maritimes (36 populations au total). Des tetraploides (2n = 28, 23 populations) se trouvent presque exclusivement dans les Pyrenees et dans le Nord-Est du Massif Central. Des hexaploides (2n = 42, 32 populations) etaient repandues dans le reste de la region etudiee, avec des presences sympatriques dans le Massif Central ou les aires de la cytotype diploide, tetraploide et hexaploide se rencontrent. Dans cette region un grand nombre d'hybrides a ete trouve entre des plantes diploides et tetraploides ainsi qu'entre des plantes tetraploides et hexaploides (dans 11 populations au total). L'immense majorite des plantes a des fruits angiocarpes, independamment du niveau de ploidie, de sorte que la correlation du caractere angiocarpe avec le taxon diploide (considere dans la literature concernante comme Rumex angiocarpus Murbeck, 2n = 14) n'existe pas. Dans les Alpes Maritimes des diploides gymnocarpes ont ete trouves qui peuvent etre consideres comme un taxon primitif dans l'agglomerat en question. Selon la connaissance actuelle, la distribution de l'agglomerat polyploide du Rumex acetosella peut etre indiquee comme caracteristique de celle d'un complex qui s'est developpe pendant et apres les dernieres periodes glaciaires. Dans les discussions attention a ete pretee aux causes eventuelles de ces differences de distribution (p.e. l'augmentation vegetative aux niveaux de ploidie plus eleves). Afin d'obtenir une opinion plus complete sur ce complexe les recherches seront continuees.
- Published
- 1974