Cytotaxonomy of some species of Acanthophyllum (Caryophyllaceae) from Iran

Original observations on meiotic cells in 17 species of the genus Acanthophyllum are reported. Of these, the chromosome numbers, for 8 taxa viz, A. laxiusculum, A. heratense, A. caespitosum, A. pachycephalum, A. khuzistanicum, A. mucronatum, A. verticillatum and A. crassinodum are new observations. The basic chromosome numbers for the genus are x = 14 and x = 15. Three ploidy levels were observed for x = 15, diploidy (2n = 2x = 30), tetraploidy (2n = 4x = 60) and hexaploidy (2n = 6x = 90). Comparison of the morphological characters, chiasma average and chromosome configuration have shown some similarities between three tetraploid species of A. microcephalum, A. mucronatum and A. verticillatum and two hexaploid species of A. crassinodum and A. glandulosum. A. caespitosum is quite different from the others, especially in chromosome number (n = 14) and the morphology of inflorescence. Therefore, it seems that this taxon should be placed in a new section. The occurrence of polyploidy in some species indicates that this phenomenon plays an important role in the evolution of the Acanthophyllum genus. Chromosome configurations for polyploid species and chiasma average for all species are reported here for the first time.