Morphological and anatomical characteristics and taxonomical significance of achene micromorphology of Achillea phrygia and A-gypsicola (Asteraceae), endemic to Turkey

Micromorphological and anatomical characters of two Achillea L. species, A. phrygia Boiss. & Bal. and A. gypsicola Hub-Mor., which are endemic to Turkey, were investigated. It was observed that stem length, corymb width, number of capitula and median phyllary shape were diagnostic characters. In the anatomical studies, cross sections were taken from roots, stem and leaves. It was observed that roots of the investigated taxa had a secondary thickening. Endodermis and collenchyma layers were prominent in the stem of both taxa and they had a bifacial mesophyll while the layers of the mesophyll varied. Stomata were anomocytic in both species. We found that there was a significant difference in terms of width of epidermis cells and length of cortex cells in the root, epidermis width and length, collenchyma and parenchyma cells, endodermis length, diameter of trachea of stem, length of upper epidermis cells, width of lower epidermis cells, length of palisade parenchyma and spongy parenchyma cells, diameter of trachea and stomata length of leaf between the two taxa (p < 0.05). Scanning electron microscopy (SEM) was used to describe the micromorphology of trichomes and achenes. In A. phrygia, long and eglandular trichomes were more dense on the stem and leaf epidermis. Achene micromorphological characteristics such as size, shape and achene coat were considered to be useful in separating the investigated species.