hybridsTragopogon

Tragopogon hybrids refer to naturally occurring hybrids and polyploid lineages within the genus Tragopogon, a group of flowering plants in the Asteraceae commonly called goatsbeards or salsifies. Among the best documented examples are two allopolyploid species that formed in North America from the hybridization of two diploid parental species: Tragopogon dubius (yellow salsify) and Tragopogon porrifolius (purple salsify).

Tragopogon miscellus and Tragopogon mirus are tetraploids (two complete chromosome sets from each parent; 2n = 24) that arose when hybrids between T. dubius and T. porrifolius underwent chromosome doubling, restoring fertility and allowing stable reproduction in the wild. These allopolyploids have established multiple, geographically scattered populations and show substantial phenotypic variation, often displaying traits influenced by both parents.

Significance and characteristics: The case of T. miscellus and T. mirus is widely cited as a classical example of rapid polyploid speciation and reproductive isolation through allopolyploidy. Genetic and cytogenetic studies demonstrate that the new species contain genome contributions from both parental lineages and can exhibit novel chromosomal interactions that promote fertility. Morphologically, hybrids can resemble one parent, an intermediate form, or display a mix of diagnostic traits from both species, reflecting the genomic merger.

Distribution and study: These hybrids illustrate ongoing processes of speciation in plant populations and have been the subject of long-standing research on polyploid evolution, genome duplication, and the dynamics of hybrid zones in natural settings within North America.

See also: Polyploidy, Speciation, Asteraceae, Tragopogon.