Taxonomic implications of anatomical characteristics of the genus Tulipa (Liliaceae) in Turkey and their place in the historical subgeneric classifications

Abstract

This paper comprehensively discusses anatomical features of the genus Tulipa (Liliaceae) in Turkey. These are compared with the current subgeneric classification. Anatomical structures, including transverse sections of the root, stem (scape) and leaf, and surface sections of the leaves are illustrated based on the 420 preparations obtained from 42 OTUs (populations) belonging to 18 taxa. Densities of stomata and epidermis cells per unit leaf area (mm2), stomatal index and ratio of stomata index on the leaf surfaces were also calculated. Cluster and principal component analyses (PCA) were employed, and all results were compared at the population level. In this anatomical study, some significant differences were found among Tulipa taxa, especially at the infrageneric and interspecific levels. The results of anatomical investigations are consistent with published results of previous morphological and molecular analyses. The results of cluster analysis and PCA support the classifications of Veldkamp & Zonneveld and Christenhusz et al. including three subgenera, Eriostemones, Tulipa and Clusianae, but subgenus Orithyia was not included in this study because it is absent from Turkey. Subgenus Eriostemones is divided into two sections, Sylvestres and Saxatiles, following treatments by Baker and Eker et al. In subgenus Tulipa, although morphometric analyses partially supported the taxonomic grouping previously proposed as three separate sections, Tulipa, Tulipanum and Eichleres, it also clearly indicates that considering them as a single section (Tulipa) is perhaps a better option.