The aim of the present study was to analyse the support for reducing Chaerophyllum karsianum and C. posofianum, both local endemic to northeast Anatolia, to synonyms of C. bulbosum. Chaerophyllum karsianum is closely related to C. bulbosum but may be distinguished from it by its pink petals, ciliate bracteoles, entire leaf segments and 12–16 rays. Chaerophyllum posofianum is also closely related to C. bulbosum but differs from it by its entire leaf segments, ciliate bracteoles and purple anthers. However, our field observations and examination of herbarium specimens showed that all these diagnostic morphological characters overlap. The flower color of C. bulbosum ranges from white to purple within populations or even individuals, and the bracteole margin ranges from entire to ciliate. We also investigated and compared the anatomical and micromorphological characteristics of fruits of C. bulbosum, C. karsianum and C. posofianum, but found no diagnostic differences. Furthermore, nucleotide sequence data generated for the present study showed that the internal transcribed spacer sequences of C. karsianum and C. posofianum were identical to those of C. bulbosum. Our results thus strongly support that C. bulbosum, C. karsianum and C. posofianum are conspecific.