Cytology of some species of the Ophioglossaceae in India

Abstract

Chromosome numbers in six species of Ophioglossum available in Poona and in Helminthostachys zeylanica L. obtained from Kerala are given. O. nudicaule L., O. gramineum Willd., O. pedunculosum Prantl (sensu non-Desv.) and O. fibrosum Schum. were found to have n=120 chromosomes. O. aitchisoni d’Alm. had 210-215 bivalents, and O. reticulatum L. had n=420. Of these the chromosome number in O. peduculosum was not reported before. Meiotic cycle in this species showed some irregularities such as bridge formation in some cases at anaphase I. The paper further discusses the significance of polyploidy observed in O. nudicaule and traces the evolutionary trends seen in the genus on the basis of the chromosome numbers. There exists some sort of correlation between the size of plants and their chromosome numbers. No variation in the number of chromosomes in different plants of the same species growing in different localities was observed. On the basis of the chromosomal analysis, it seems that O. nudicaule, O. gramineum group is more primitive and O. aitchisoni, O. reticulatum groups more advanced. This agrees with the conclusion drawn by one of us (Mahabalè, 1965) in this regard, on the basis of the morphology of species.