Some notes on the types of pollen aperture in the genus Crocus L. (Iridaceae)

Abstract

Crocus L. (Iridaceae) is systematically a very problematic genus due to the lack of clear distinctive features, wide range of habitats and the heterogeneity of morphological features. This genus is also highly heterogeneous from a karyological point of view. Apart from the most common spiraperturate pollen grains in Crocus, the authors frequently mentioned a number of other aperture types for individual species (subspecies, variations, etc.), i.e. polyrugoidate, nonaperturate (inaperturate), polyaperturate, with more or less extensive furrows, with short furrows, etc. The purpose of this work is to perform a palyno-morphological analysis of pollen aperture types noted in the genus Crocus. The reason for the study is a significant disagreement among researchers when describing the types of pollen apertures in the genus Crocus. An analysis of the literature, as well as the results of our previous studies, showed that the genus Crocus is characterized by inaperturate (nonaperturate), polyaperturoidate, spiraperturate and net-like pollen apertures. The similar net-like apertures were observed for some representatives of the subgenus Scorpiris Sach of the genus Iris L., in particular, in Iris atropatana Grossh. In our opinion, this aperture type can serve as a link between the genus Crocus and the subgenus Scorpiris of the genus Iris. We suggest, that the spiraperturate pollen type mentioned most often for the representatives of the genus Crocus can be considered the basic type within the genus. On the other hand, formless aperture-like areas are genetically unstable transitory variations, which occurred arbitrarily due to mutations. Finally, “polyrugoidate” (or with net-like apertures) pollen type noted in the literature for C. chrysanthus subsp. punctatus F.Candan et N.Özhatay may be considered to be more advanced in the genus Crocus