Pollen morphology and systematical contribution of some Onosma (Boraginaceae) taxa distribution in Turkey

In this study, the palynological characteristics and its taxonomic implications of 30 different Onosma L. taxa, which belong to sections Protonosma M. Popov., Podonosma (Boiss.) Gurke. and subsections Haplotricha (Boiss.) Gurke., and Asterotricha (Boiss.) Gurke. of section Onosma were investigated under Light Microscope (LM), Scanning Electron Microscope (SEM) and pollen of four taxa with Transmission Electron Microscope (TEM). Pollen grains are mostly heteropolar and trisyncolporate rarely isopolar and tricolporate (O. rostellata and O. orientale), subprolate or prolate to spheroidal and exine tectate-perforate (O. rostellata, O. sericea and O. auriculata) and tectate-imperforate (O. bracteosa). In the conclusion of the study it has been determined that investigated Onosma species have shown three different types of ornamentation, namely scabrate (O. sericea type, O. auriculata type and O. orientale type), rugulate (O. rostellata type) and scabrate-rugulate (O. bracteosa type). It was pointed out that these different types of ornamentation can be used to separate the sections and similar taxa from each other. Pollen grains of O. lycaonica Hub.-Mor., O. bracteosa Hausskn. & Bornm., O. caerulescens Boiss. and O. taurica Willd. var. taurica from subsection Asterotricha have an operculum.