Pollen dimorphism in Acacia asak (Forssk.) Willd. (Fabaceae: Mimosoideae)

Abstract

The study of pollen grains of Acacia asak showed a marked pollen dimorphism of smooth exine (psilate) polyad type A and rough exine (scabrate) polyad type B, when examined using light microscopy (LM) and scanning electron microscopy (SEM). Typical pollen grains of Acacia asak are 16-monads. Both acetolised and non-acetolised grains of the two types were studied, measured, described and illustrated using LM and SEM. The main differences between these and the functional significance are discussed. Polyad dimorphism can be used as a character to distinguish between A. asak and otherAcacia species. In this study, two polyad types are recorded from the same anther of A. asak for the first time, possibly related to pollination function. However, the function of polyad dimorphism in the same anther is still unclear and requires further study.

Keywords:

• Acacia asak
• dimorphism
• harmomegathy
• Mimosoideae
• pollenkitt
• polyad
• sculpture

Acknowledgements

I would like to thank the late Prof. Dr. R. Stösser, Institut für Sonderkulturen und Produktionsphysiologie (370), and F.G. Obsbau, University of Hohenheim, Stuttgart, Germany, for his help and for his great care during my stay in Germany. Deutscher Akademischer Austauschdienst (DAAD) supported this work through a short scholarship.

Additional information

Notes on contributors

Heba Elazab Mohamed Elazab

HEBA ELAZAB is a lecturer in plant taxonomy and palynology at Ain Shams University, Cairo, Egypt. She worked as an Assistant Professor at King Faisal University, Saudia Arabia between 2008 and 2011. Heba's research interests are on botany, palynology, plant anatomy and plant taxonomy. She received a PhD scholarship from the Deutscher Akademischer Austauschdienst (DAAD) in 2003. Heba is a member of the Egyptian Botanical Society, the Linnean Society and the Systematics Association.