Pollen morphology and folding of Prototulbaghia Vosa (Amaryllidaceae), South Africa

Abstract

Prototulbaghia is a genus within the Tulbaghieae in subfamily Allioideae (Amaryllidaceae) and comprises two species restricted to the northeastern escarpment of South Africa. The pollen morphology of these species is studied with the use of scanning electron and transmission electron microscopy. The pollen is compared with that of representatives from the sister genus Tulbaghia (Tulbaghia simmleri and Tulbaghia violacea) and sister tribe Leucocoryneae (Nothoscordum borbonicum). The pollen morphology of Prototulbaghia differs from other members of the Allioideae in both the shape of the pollen grains and the ornamentation of the sulcus membrane. The pollen grains of both Prototulbaghia species are oblate-spheroidal with a reticulate surface ornamentation, the sulcus membrane contains sexine elements (pila), and the wall is thick. Dehydrated grains of both Prototulbaghia species are also triangular in shape after folding due to the length of the sulcus and the thickening of sexine elements in the centre thereof. This type of folding is proposed as a taxonomic character to distinguish the dehydrated pollen grains of this genus from pollen grains of other members of the Allioideae