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Anatomical and palynological characteristics of endemic Onosma polyantha DC. and Onosma mitis Boiss. & Heldr. from Turkey

Huseyin Suna, Macide Burcu Timur, Sertan Cevik and Riza Binzet

In this study, the anatomical and palynological characters of Onosma polyantha DC. and Onosma mitis Boiss. & Heldr. endemic to Turkey was investigated. To determine the anatomical characteristics, transverse sections of the root, stem and leaves, as well as adaxial and abaxial sections were taken from the leaves. It was determined that both species had a thick periderm tissue at the outermost part of the root. The endodermis was clearly observed and the pith was composed of tracheal elements. In the cross-section of the stem, only setose hairs were observed in O. polyantha, whereas in O. mitis, both setose hairs and rarely glandular hairs were present. The stomata were found to be at the same level as the epidermis in the O. mitis, while they were ± the upper level of the epidermis in O. polyantha. Two types of stomata (anomocytic and anisocytic) were seen on the lower and upper surfaces of the leaves, the density of the stomata was also higher on the lower surface of leaves in both species. In contrast, the stoma index was higher on the upper leaf surfaces than that of the lower side. The leaves were dorsiventral (=bifacial) in O. mitis and equifacial (=izobilateral) in O. polyantha. The pollen of both taxa were heteropolar, O. polyantha pollen grains were trisyncolporate at the distal pole, while in O. mitis pollen grains were trisyncolporate and tetrasyncolporate. Apocolpium was observed in the proximal poles of the trisyncolporate pollen, whereas it was not observed in the tetracolporate pollen of O. mitis. The pollen shape was spheroidal P/E=1.12 in O. polyantha and subprolata P/E=1.15 in O. mitis. In both species, the sculpture was scabrate (=granulate) and scabras were distributed on the surface of the pollen homogenously. The nutlet morphology of O. polyantha and O. mitis were also examined the nutlet ornamentations were reticulate, rugose, and reticulate-rugose, respectively; and epidermal cells were seen in different sizes. The aim of this study is to determine the anatomical and palynological characteristics of O. mitis and O. polyantha and to provide a more reliable diagnosis with the help of these characters.

To Cite this article: Suna, H., M.B. Timur, S. Cevik and R. Binzet. 2021. Anatomical and palynological characteristics of endemic Onosma polyantha DC. and Onosma mitis Boiss. & Heldr. from Turkey. Pak. J. Bot., 53(6): DOI:

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