Onosma-Flora of Iran

Onosma L. (Boraginaceae, Lithospermeae) is both a species-rich and an Irano-Turanian characteristic genus with near 258 species distributed from W Mediterranean to C Asia. Türkiye followed by Iran harboring respectively over 104 and 75 species are considered as the most important centers of both diversity and endemism of this old world genus. The present study reports the wide-spread Euro-Siberian species O. tinctoria as a new record for the flora of Iran. Furthermore, the first collections of O. stapfii since its type sampling are documented. The recent species had long been treated as a synonym of O. microcarpa. Supported by conspicuous diagnostic features, O. stapfii is herein suggested to be resurrected and considered again as a distinct valid species. Also, based on field and herbarium investigations the unnoticed occurrence of the Mediterranean-Irano-Turanian species O. echinata in Iran is confirmed. The species are described and their distribution in Iran is mapped. Beside the provided floral slides, photos, and IUCN risk categories, some ecological data about the species are presented. Proper identification keys for recognizing the discussed species among their allies are also designed. Finally, morphologic comparisons indicated that shape, and size of calyx, bracts, and corolla, ciliation of nectariferous rings, shape, color and sculpture of nutlets as well as the trichome coverage may provide the most distinguishing characteristics between close species.