Karyology of Plagiomnium. I. Plagiomnium affine (Schrad.) T.Kop.

Variability in chromosome numbers of Plagiomnium affine from five populatio ns in Poland was found with n = 6, 7, 12 and Is. Three populations showed i ntrapopulation karyological variability (n = 6, 12, 18), two others were ka ryologically uniform (n = 6). Additionally, mixoploidy was noted with haplo id (n = 6, 7), haploid-diploid (n = 6, 12) and haploid-diploid-polyploid (n = 6, 12, 18) cells in one gametophytic apex. The haploid set consists of two chromosome types: metacentric and submetace ntric. Their frequency in particular metaphase plates was different. Variat ion in karyotype was discovered within the population and among populations . Four types of karyotype were distinguished: 4m + 2sm, 3m + 3sm, 5m + Ism, 2m + 4sm. The C-banding demonstrated one chromosome with a large telomeric heterochro matin block and one intercalary band. This chromosome was the fifth in the haploid complement according to chromosome length and was the only chromoso me marker that is easy to identify in the C-banded karyotype. Centromeric b ands were not observed.