LM and SEM studies of selected southern African Vachellia and Senegalia pollen

Abstract

A palynological study was carried out on selected and commonly occurring Vachellia and Senegalia species in South Africa. This study aimed to identify pollen morphological characters that distinguish the two African genera and species, thereby enhancing their taxonomic classification and facilitating the identification of fossil pollen in palaeoenvironmental studies. Flowers of eight species, consisting of six Vachellia and two Senegalia species, were collected from the C. E. Moss Herbarium, University of the Witwatersrand, South Africa. The pollen samples were subjected to the acetolysis method of Erdtman, and light microscopy and scanning electron microscopy studies were conducted. Pollen characteristics of the studied Senegalia species (S. galpinii and S. caffra) differ from those of the Vachellia species (V. davyi, V. abyssinica, V. arenaria, V. karoo, V. grandicornuta, V. hebeclade, and V. nebrownii), as Vachellia possess colporate apertures, 36 monads, and foveolate exine sculpture with an undulating sexine and conspicuous columellae. Senegalia species, however, are porate, 16-monad, with psilate exine sculpture that is continuous and without columellae. The studied species’ pollen character differences can help separate Vachellia from Senegelia but not within the genera.