Chromosome Numbers and Behavior in Some Species of <i>Dioscorea</i>

Abstract

Chromosomes were counted at meiosis and mitosis in 4 sapogenin-bearing species of Dioscorea and 9 other species. Chromosome numbers of 7 New-World species are reported herein for the first time. In these, 2n numbers were 36 except in two lines of D. floribunda which contained 54-chromosomes and showed irregular meiosis. All New-World species counted had chromosome numbers which are multiples of 9, whereas all Old-World species had numbers which are multiples of 10. The significance of the findings is discussed with reference to origin and distribution of the genus, processes of speciation, and possible barriers to breeding.