Palynological study on a number of Iranian species of Myosotis

Abstract

The genus Myosotis, or “forget-me-not", has a global distribution in most of the temperate regions of both Northern and Southern hemispheres, a number of its species are used as ornamental plants. In order to clarify the taxonomic relationships of the species of this genus, pollen grains of 14 species were prepared from the T and FAR herbaria and were examined by means of a light microscope (LM) and a scanning electron microscope (SEM). Thirty-one characteristics such as pollen size, shape, surface type and the type, number and size of apertures studied and analyzed by PAST, PCA and IQ-TREE software, and subsequently, phylogenetic trees are drawn. The results indicated that, the species M. ramosissima and M. diminuta and the species M. lithospermifolia 1 and M. sparsiflira found to be closely related to each other as they were clustered together. Moreover, pollen shape dimorphism was identified in the two species of M. lithospermifolia 1 and M. minutiflora while the results of PCA analysis and clustering on the basis of palynological traits placed these species together. The characteristics of the polar axes length in the equatorial view with a light microscopeand diameter of equatorial or polar axes in light microscopy, the relative length of polar axis to equatorial axis of Psedocolpi, and the presence of Ubisch bodies in the polar head of pollen grains have been found to be valuable for the clustering of taxa pollen grains of M. lithospermifolia, M. sparsiflora, Myosotis sp., M. diminuta, M. propinqua, M. olympica, and M. anomala were studied for the first time. The identify key is provided based on examined the pollen grains characters. The non-monad of pollen grains for the first time from Boraginaceae in the form of the diversity of pollen grains of the species M. lithospermifolia 1 was reported.