Pollen morphology of Prototulbaghia Vosa: A comparative palynological study of the Southern African Alliaceae.

Abstract

The  Southern  African  Alliaceae  Borkh.  is  represented  by  four genera (Allium L., Nothoscordum Kunth, Tulbaghia L. and Prototulbaghia Vosa) and 28 species. The  pollen  morphology  of  the  endangered  monotypic  genus Prototulbaghia has  not  been described  before.  A  comparative  study  of  the  pollen  morphology  of Prototulbaghia  siebertii Vosa, Nothoscordum  borbonicum Kunth, Tulbaghia  simmleri P.Beauv.  and T.  violaceae Harv.  is presented in this article. Scanning electron microscopy, as well as light microscopy, were used to examine the pollen. The pollen morphology of the species can be described as perprolate and monosulcate, and the surface sculpture as reticulate and heterobrochate. However, the pollen of Prototulbaghia siebertii displays a unique characteristic as the grains are folded in their breadth with the tips touching, hence causing the grain to display a triangular and disulcate appearance. It might be possible to ascribe this fold to the process of harmomegathy or a still unknown event that occurs during the development of the pollen grain. This phenomenon should be further investigated to determine the cause of folding and whether it is a unique taxonomic  characteristic  of  this  genus,  and  if  it  could  be  of  evolutionary  significance  for the Alliaceae.