Article

Centaurea grbavacensis, a Balkan endemic species of North Macedonia and N and C Greece, has been thoroughly studied throughout its distribution, based on living, photographic and herbarium material as well as literature. Ιt was found that all forms of the species grow in both Greece and North Macedonia. We studied the variation of the main morphological features, especially for the Mt. Olympos (Greece) subpopulations. It was found that spine length of the involucral phyllaries varies significantly within individuals and subpopulations, irrespective of flower colour (the typical colour is dark brownish purple, whereas in C. grbavacensis f. lutea it is yellow). Therefore, C. grbavacensis f._ spinescens_ cannot be maintained as a separate taxon. A karyological study of the two colour forms was performed, and karyotype photos are provided for the first time. The chromosome number, 2_n_ = 2x = 22, was confirmed and the karyotype morphology is mentioned.