There is a significant lack of specific characteristics for distinguishing cultivars of sweet chestnut (Castanea sativa Mill.). The study investigates the diagnostic suitability of flowering phenology and morphological characteristics of C. sativa. A whole variety of such are specific for cultivars. In particular, the interrelation between various phenological phases can supply valuable site-independent characteristics (e.g. degree of protogyny, catkin fall in relation to the phase of full female flowering). Furthermore, many structural characteristics of the differing types of inflorescence have a variation specific to the cultivars (e.g. catkin length, mode of shoot branching) apart from the known morphological characteristic of the stamina type (length of stamina). Floral characters are very important for the distinction of cultivars of C. sativa.