Karyotype differentiation and its consequences in Mediterranean « Limonium »

Summary Within the genus Limonium (Plumbaginaceae) the following chromosome numbers occur in the Old World 2n = 12, 14, 16, 18, 25, 26, 27, 32, 34, 35, 36, 42, 43, 54. Many of the species are apomictic. It can be shown that all species with chromosome numbers higher than 18 (perhaps with the exception of 2n = 32, 36 and 54) are hybrids basing on x = 8 or x = 9 or of the combination of both numbers. X = 8 could have its origin by fusion of two chromosomes of x = 9. Since one pair of large metacentric chromosomes appears in all x = 8 chromosome sets (with exception of the species L. sinuatum, L. diffusum and L. ferulaceum, which form rather isolated groups within the genus). The pollen grains and the stigmas of the amphimictic species are dimorphous. Cross pollination there is necessary. Within one population of the other species normally only one type occurs. Nevertheless these plants too show a high degree of fertility—another hint for its apomictic status.