Nutlets micromorphology of some Onosoma L. (Boraginaceae) species from Turkey

Morphological and micromorphological characters of the nutlets of ten Onosma species in Turkey were reported. Studied fruit surfaces show some variations. Based on the structure and patterns of epidermis cells of the nutlets, two principal types can be distinguished. In Type 1, the epidermal cells of the nutlet surface are formed in a reticulate pattern with varied sizes and shapes of the meshes. This type is the most common type in the studied species. Seven of the species observed belong to the reticulate type, i.e. O. bracteosum, O. mutabile, O. aleppicum, O. bornmuelleri, O. aucheranum, O. araraticum and O. tauricum. In Type 2, the epidermal cells of the nutlet surface are formed in an elongated type with varied sizes and shapes. Three of the observed species belong to this type, i.e. O. roussaei, O. isauricum and O. stenolobum. Significant taxonomic differences between species were determined on the surface of the nutlets.