Taxonomic significance of achene morphology in the genus Centaurea L. (Asteraceae)

Achene morphology of 49 taxa of the genus Centaurea L. was studied in terms of 19 different characteristics. On the basis of the variation in these features, some sections, such as sect. Cyanus with hairy hilum, were separated. Despite various differences, C. leuzeoides and C. gilanica were categorized in the section Psephelloideae, a section with lots of character variations within its species. Also, C. albonitens has different characteristics in comparison with other taxa within section Phaeopappus, for example features such as pappus color and the ratio of pappus length to that of achene separated the species from other members of the section. The last but not the least, highly different characteristics were observed in the achene morphology of C. phlomoides as compared with other species in section Cynaroides. Differences such as short pappus and hilum length were found to separate C. phlomoides from other members of sect. Cynaroides. In conclusion, on the basis of the findings of this research, most achene morphological characteristics can be appropriately used as key features for the differentiation of sections in the genus Centaurea. An identification key based on the features of the achene, images related to the achene of the studied species were also presented.