Anatomical investigations on some species of Onosma L. (Boraginaceae)

In this study, 6 Onosma L. species (O. discedens Hausskn. ex Bornm.(endemic), O. tenuiflorum Willd., O. aucheranum D.C., O. roussaei D.C., O. rigidum Ledeb. and O. trapezunteum Boiss. & Huet ex Hand.-Mazz.(endemic)) were examined in terms of anatomical features.Plant materials were collected from Eastern Black Sea Region and Erzincan in the periods of their vegetation between 2003 and 2006. The collected plants were stored as herbarium and fixation materials. For anatomical investigations, transverse sections were taken from the stems, transverse and peripheral sections were taken from the leaves of the fixation materials. Permanent slides were prepared from these anatomical sections and photographed by Olympus BX51. In addition, drawings were carried out these slides.The anatomical structures of species are compared with each other and some differences among species have been also observed. It is determined that the most important anatomical differences are present in leaves. These differences are length and layer number of palisade parenchyma cells in mesophyll, the features of stomata, epiderma cells and hairs on the leaf surface. In addition, some differences in the shape and layer number of the parenchyma cells in cortex and pith are also observed in stems.