Wild cherries, petioles and geography: response to locational and elevational trends in Turkey

Widely distributed plants demonstrate a number of anatomical differences that help them adapt to the variable abiotic factors across their ranges, which in turn contributes to intraspecies variation. The genus Prunus subgenus Cerasus (Mill.) A.Gray is distributed across the three major phytogeographical regions (Mediterranean, Euro‐Siberian and Irano‐Turanian) of Turkey and on either side of the major geological divide known as the Anatolian diagonal. According to the Köppen–Geiger climate classification, Türkiye features 10 subclassifications in the arid semi‐arid (B), temperate (C) and continental (D) zones. To explore how these affect the variation of this taxonomically complex subgenus, we examined the petiole anatomy of 63 individuals of its 10 species collected from across the country, characterizing their differences on a taxonomic level and investigating geographical and climatic sources of variation. To explore the variation in petiole anatomical characters, we employed multivariate linear and logistical regression analyses using altitude and coordinate data, as well as phytogeographical region and position in relation to the Anatolian diagonal, as independent inputs. The results indicate that geographical position and altitude had an effect on petiole and vascular bundle dimensions, while climate zone is an important source of variation in cortex layer number and nodal pattern for some species. Analysing the group as a whole also yields some insight into the differences that may help species adapt to their specific surroundings. Additionally, we discuss differences in petiole anatomy among species, their implications for taxonomy and provide a key based on petiole cross sections.