Some notes on taxonomy and diversity of Onosma with emphasis on important evidence and complex groups in Flora Iranica

Onosma L. as a rich taxa in Boraginaceae including about 150–180 species, centered mainly in Irano-Turanian region. The genus faced with several systematic complexities lead to many identification problems as well as morphological polymorphism. Several authors have used setae characteristics in Onosma as the most important diagnostic evidence in delimitation and classification of species in addition to the natural group. Besides palynological and karyological studies, molecular evidences have also confirmed recent classifications. This genus has been classified as a sister to Maharanga A.DC as a central Asiatic taxon of Boraginaceae. Several ambiguities in identification and differentiation of species created a wide range of complexities among and also between the species. Onosma elwendicum Wettst., O. bulbotricum DC., O. rostellatum Lehm., and O. dichroanthum Boiss. are some examples facing with these problems. Also, Onosma olivieri H. Riedl., and O. lanceolatum Boiss. & Hausskn. as closest taxa in Flora Iranica, eventually are geographical ecotypes and can be synonym taxa. Besides this, some taxa following O. sharifii H. Riedl., O. paboti H. Riedl., and O. caeurelescens Boiss. do not have detectable type specimens with no specimens obtained from type localities. Therefore, every comment on taxonomy as well as systematic study of the genus, need to a perfect assessment of diverse ecotypes and geographical populations together with a detailed field works with emphasis on ecology and phytogeography of their habits.