Taxonomic significance of anatomy and achene micromorphology of selected Cousinia Cass. species (Asteraceae)

Background and Aims: The genus Cousinia has about 700 taxa all over the world. It is a hard and controversial group to classify in terms of taxonomy. This study aims to determine the achene micromorphological and anatomical characteristics of two selected Cousinia species, as well as their taxonomic significance. Methods: In anatomical studies, the sections were set in paraffin, cut with a microtome, and stained with safranin-fast green. For both C. eriocephala Boiss. & Hausskn. and C. calocephala Jaub. & Spach species selected, an independent sample T-test analysis was performed using quantitative data to determine the importance of anatomical characters. In addition, PCA analysis and heatmap analyses were performed. SEM images were taken to determine the micromorphological features of the achenes. Results: In the transver section of stems in C. eriocephala, from the epidermis to the center, there are 9-12 rows of cortexs layers composed of parenchymatic cells. In the transver section of stem in C. calocephala from the epidermis to the center, there are 5-8 rows of cortical layers composed of parenchymatic cells. In the cross-sections of the leaf in C. eriocephala, it was determined that the midrib shape was semi-orbicular, and a total of 9 vascular bundles, 3 large and 6 small, were counted. In the cross-sections of the leaf in C. calocephala, it was determined that the midrib shape was semi- orbicular, and a total of 6 vascular bundles, 3 large and 3 small, were counted. The achene surface ornamentation of C. eriocephala is striate-scrobiculate, while C. calocephala is striate and scrobiculate-faveolate. Conclusion: According to the findings, it was determined that anatomical characters are important in the differentiation of species, as supported by both PCA and heatmap analysis. Keywords: Asteraceae, Cousinia eriocephala, C. calocephala, Plant anatomy, Principal component analysis, Turkey