Karyotypes of tragopogon (Compositae: Lactuceae)

Abstract

Karyotypes of 24 diploid (2n=12)Tragopogon species are similar with one long pair of chromosomes (A), two medium-length pairs (B and C), and three short pairs (D, E, and F). These species may be divided into three karyotypic groups: 1) seven species with a satellite on A and on D; 2) 14 species with a satellite on A only; and 3) three species with a satellite on D only. Most species within karyotype groups may be separated from each other either by distinctive features of certain chromosomes or by statistical differences in length of chromosome arms or long arm: short arm ratios of chromosome A. Three tetraploid (2n=24) species had two long pairs (A,A′), four medium-length pairs (B,B′;C,C′), and six short pairs (D,D′;E,E′;F,F′). Suggestions are made as to the putative diploid parents of these presumed allotetraploids.