Foliar anatomy of some Prunus L. subgen. Cerasus Mill. (Rosaceae) taxa

Abstract

Prunus L. subgen. Cerasus Mill. (Rosaceae) contains numerous economically important species, including fruit trees and ornamental plants. This study compares the leaf anatomy and calcium oxalate crystal types of 98 individuals of 14 Prunus subgen. Cerasus taxa from Turkey. We stained leaf sections with Safranin-Alcian Blue double stain and mapped calcium oxalate crystals under light microscope with polarized light. We used one-way ANOVA to determine the statistical significance of quantitative data. Significant quantitative and qualitative data were analyzed using PCoA to establish relationships among taxa. We observed three different crystal distribution patterns and three crystal types, finding druses present in all taxa, while some taxa also have sand or prismatic forms. Most characters showed high variation. Our analysis shows that vascular bundle, midrib, upper epidermis and lower epidermis width/length ratios; midrib epidermis, upper epidermis and phloem cell lengths; upper epidermis and lower epidermis cell widths and lower cuticle thickness are not taxonomically useful, while features of the bundle sheath, epidermis cell surface, phloem fibers, mesophyll layers and angle of blade between the midrib can be used in conjunction with other characters to distinguish certain taxa. Overall, PCoA delineated two rough groups, separating P. avium, P. cerasus and P. mahaleb from the rest of the studied taxa. In investigating the anatomical variation between different individuals of these taxa, we found that some features previously used in infraspecific taxa, such as trichomes, varied sometimes even within an individual, casting doubt on the wisdom of using these for systematic work in subgenus Cerasus.