Medicago sativa species complex: Revisiting the century‐old problem in the light of molecular tools

The genus Medicago is an important component of legumes and includes the model legume barrel‐clover ( Medicago truncatula Gaertn.) and widely cultivated forage crop alfalfa ( M. sativa L.). The complex taxonomic group known as the M. sativa species complex, or M. sativa–falcata species complex, includes a number of taxa along with cultivated alfalfa that naturally distributed throughout northern Eurasia. Largely because of the millennia‐long economic importance, the taxa have been in the center of attention. In the context of the efforts to understand taxonomic units included in the complex, a wide range of tools have been exploited. The early tools available were morphological traits such as flower color, pod shape, and pollen shape. The large conflict and discrepancy among researchers regarding the statue of the taxa sourced from the fact that a few genes controlled each of the morphological traits used. Thus, the morphology‐based classification was proved to be contradictory. As the molecular tools became available and the research intensified, the initial species status generously granted to the taxa was questioned, and all the taxa denoted as species earlier were relegated to subspecific level. We are aiming to provide an up‐to‐date comprehensive picture for the complex in the light of recent molecular studies.