Chromosome polymorphism and nucleolar organization in some species of Fritillaria Linn.

Abstract

Morphology of the chromosome complements of the two N W Himalayan species is at variance with those from other places particularly in respect of centromeric position and the size and number of nucleolar organising regions. Whereas past work on F. roylei put the number of NOR's at two and eight per diploid set, present work has revealed occurrence of ten such regions. Again in F. imperialis present observations indicate the presence of four NOR's against two suggested by earliar workers. Support for the authenticity of present counts has been drawn from the number of nucleoli organized per nucleus. Structural variability in chromosomes particularly the ones bearing secondary constriction, appears to be the major source of evolution within the genus.