Distribution, ecology and macro- and micromorphology of the genus Melissa in Istria and on the islands of the Kvarner Bay

The island of Krk with an area of 405,78 km2 presents a very rich flora (1525 species) includingsome very special rare and unique taxa (Rottensteiner & Zernig 2020). This island is covered by thetypical vegetation of the submediterranean zone (mixed Quercus pubescens woods and šibljak), justin the southernmost parts, around Baška and Stara Baška with transitions to eumediterraneanvegetation. The genus Melissa (Lamiaceae) in Istria is represented by two species, M. officinalis ssp.officinalis and M. romana (Rottensteiner 2014, 2018). M. romana was recorded here for the first timein SE Kras, Krk Island in June 2019 (Dolovo), shortly thereafter also at the west coast near Njivice(Padure 2019) and new locations in Nivice and Vrbnik (Padure 2021). In the past, M. romana wasconsidered a variety of M. officinalis (lemon balm) and catalogued as M. officinalis subsp. altissima.Montelucci (1953) considered it as a case of stabilized polyploidy (M. romana 2n=64; M. officinalis2n=32) as it does not generate any offspring and it has an intermediate aspect when it grows besideM. officinalis (Miceli et al. 2006, Pignatti 2018, 2019). Our research presents the distribution of genusMelissa with ecological, macro- and micromorphological (SEM) characteristics of vegetative andgenerative organs that differentiate the species.