Taxonomic classification of the genus Echinops (Asteraceae) is still unclear, mostly because of the small morphological differences between the species. Estimation of genome size is helpful in species identification and in establishing a relationship between them; however, nuclear DNA content has been established for only 25% of known Echinops species. In the present study, in addition to the chromosome number, the DNA content of species in 22 taxa belonging to 3 sections (Echinops, Oligolepis, and Ritropsis) was estimated using flow cytometry; 9 of the species are endemic to Turkey. For 16 of the species this is the first report on their genome size. The chromosome numbers of the studied species were 2n = 28, 30, 32, or 34; the 2C DNA content ranged from 5.55 to 13.96 pg, and the mean DNA content per chromosome from 0.19 to 0.45 pg. The possible chromosome rearrangements during evolution of the genus are discussed. It is suggested that the ancestral section of the genus Echinops is Oligolepis, and the most modern one Echinops. The results allowed for the verification of the taxonomic position of some Echinops species, which previously were classified based only on morphological characteristics.