Two New Diploid Forms ofPsilotum Nudumfrom India with a note on the Evolutionary Mechanism Operative in the Taxon

Occurrence of Various Cytotypes ofOphioglossum ReticulatumL. in a Population from N. E. India

“…Associated with high grade of ploidy, this genus is one of the oldest living vascular plants amongst Pteridophytes. Observing a similar case in Psilotum nudum in which a high grade of ploidy has recently been reported by SINHA and VERMA ( 1977 ), some common advantages provided by polyploidy are discernible. Taxa with chromosome sets duplicated during the course of evolution had the greatest evolutionary potential.…”