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Par l'observation de la couleur des fleurs dans des descendances de pollinisation naturelle et de croisements chez Hedysarum coronarium L., on montre que l'allopollen est tellement favorisé par rapport à l'autopollen que 90 p. 100 des graines sont issues d'une fécondation croisée. L'étude de la compétition pollinique chez cette espèce montre également que les gènes de coloration a et b ne semblent pas avoir une liaison particulière avec un gène gamétophytique mâle. Mots clés additionnels : Autogamie, allogamie, pollinisation naturelle, pollinisation artificielle, pollinisation pluripaternelle, gène de coloration, eompétition gamétique. SUMMARY Study of pollen competition in sulla (Hedysarum coronarium L., Leguminosae) The character « prcscnce-absencc of flower anthocyanins was used as a genetic marker in the study of pollen competition in sulla (Hedysarum coronarium L.). This species was shown to be preferentially allogamous. The rate of allogamy obtained under natural and artificial pollinisation was close to 90 %. The use of different sorts of pollen in simple crosses without castration and in multipaternal pollination experiments showed that the two flower colour genes, a and b, were not apparently linked to a male gametophyte gene.

Several samples of wild populations of two subspecies of the genus Hedysarum (H. spinosissimum subspecies capitatum, an outcrosser, and H. spinosissimum subspecies euspinosissimum, a selfer) were examined with respect to variability of 25 quantitative characters and allozyme variation at 13 loci. The amount of phenotypic and genetic variation within and among populations was documented. For most of the 25 quantitative characters, the differences between population means and between the total variances of the populations were higher in the selfer than in the outbreeder. Significant among-population genetic variation was found for nearly all characters in the two subspecies, but the outbreeder had higher within-population variability than the selfer with heterogeneity among characters. However, allozyme variation at 13 loci in about the same number of populations showed higher levels of genetic variability in the outcrossing subspecies capitatum compared with the selfing subspecies euspinosissimum, based on measures of mean number of alleles per locus, mean proportion of polymorphic loci, and mean heterozygosity. Therefore, H. spinosissimum subsp. capitatum appeared to be highly polymorphic in contrast to the greater monomorphism within populations of H. spinosissimum subsp. euspinosissimum. The genetic affinities of different populations of a subspecies are uniformly high, with Nei's genetic identity ranging from 0.983 to 0.997 in the selfing subspecies euspinosissimum and from 0.922 to 1.000 in the outcrossing subspecies capitatum.Key words: Hedysarum, genetic variation, populations, electrophoresis.

Summary Baatout, H.; Marrakchi, M. & Combes, D.: Genetic divergence and allozyme variation within and among populations of Hedysarum spinosissimum subsp. capitatum and subsp. spinosissimum (Papilionaceae). ‐ Taxon 40: 239–252. 1991. ‐ ISSN 0040‐0262. Three outcrossing populations of Hedysarum spinosissimum subsp. capitatum and two self‐pollinating populations of H. spinosissimum subsp. spinosissimum were surveyed for variation at 36 allozyme loci. The proportion of polymorphic loci ranged from 25.0 to 75.0 % in subsp. capitatum and from 27.8 to 30.6 % in subsp. spinosissimum, and the mean heterozygosity from 0.088 to 0.299 in subsp. capitatum and from 0.086 to 0.097 in subsp. spinosissimum. No karyotypic differences distinguish the two subspecies, and no hybridization between the allogamous H. spinosissimum subsp. capitatum and the autogamous subsp. spinosissimum was noted. Allele frequency differences between the two subspecies indicate that they are clearly distinct in several genes coding for the enzymes peroxidase, esterase and acid phosphatase. The level of genetic divergence at the enzyme level, revealed by electrophoretic analysis of the two taxa, supports their specific distinctness, the mean genetic distance between them being 0.45 ‐ which is indicative of a long period of lack of gene flow between them.