Primary Basic Chromosome Numbers in Ferns: Facts or Fantasies?

Abstract

Several workers have attempted karyotypic analysis of ferns and con- cluded that the high chromosome numbers that characterize extant fern genera reflect high polyploidy. An examination of fern karyotypic data suggests that ob- served differences in total length and arm length ratio between chromosomes and chromosome groups are subject to many errors. The possibility of such errors sug- gests that karyotypic analysis in ferns is a dubious practice. We have applied graphic and statistical methods of analysis to karyological data previously published by Ta- tuno and others and conclude that unreasonable inferences have been made from the karyotypic data. These data are consistent with an hypothesis that fern evolution at the generic level occurred from ancestors that had essentially the same high chromosome numbers observed in living ferns. In a series of papers dealing with karyotypic analyses of ferns and fern allies, Tatuno (1963), Tatuno and Yoshida (1966, 1967), Tatuno and