Taxonomic notes of the genus Gagea sensu lato including Lloydia based on palynological features

Abstract

Pollen micromorphology and sporoderm ultrastructure of 10 species of the genus Gagea sensu lato (including Lloydia) were examined by light microscopy, scanning electron microscopy, and transmission electron microscopy. The results showed variation in all quantitative characters of pollen micromorphology. In terms of qualitative characters, oblate pollen shape and two pollen types (medium and large) were seen. Exine ornamentation of the equatorial surface differed from that of the sulcus margin region. Intine ornamentation in the sulcus region was similar in all taxa. Furthermore, the situation of the furrow among cristates and granulates in muri differed, as did the lumina connections. The qualitative and quantitative characters of the pollen sporoderm, such as the presence or absence of endexine, number of intine layers in the sulcus region, and sporoderm thickness, also varied. A dendrogram of all qualitative and quantitative palynological characters, created by the unweighted pair group method with arithmetic mean (UPGMA) based on Euclidean distances, identified six pollen types. Palynological types strongly supported the transfer of Lloydia to Gagea. However, the palynological dendrogram did not support reducing the number of sections in these taxa. A dichotomous key is also presented based on pollen micromorphology and ultrastructure.

Keywords:

• endexine
• exine
• intine
• pollen ornamentation
• pollen type
• sporoderm

Acknowledgements

Authors are special thanks to Prof. Alexander Melikian, Prof. Nonna Robertovna Meyer–Malikian and Prof. Svetlana Polevova (Lomonosov State University, Moscow, Russia), Igor Levichev (Komarov Botanical Institute of the Russian Academy of Sciences), Research Institute of Forests and Rangelands Herbarium, Tehran, Iran (TARI), Komarov Botanical Institute of RAS (LE), and Main Botanical Garden of the Russian Academy of Sciences (MHA) for their kindly helps.

Disclosure statement

No potential conflict of interest was reported by the authors.