Pollenkitt is lacking in Gnetatae: Ephedra and Welwitschia; further proof for its restriction to the angiosperms
Three members of theGnetatae (Ephedra campylopoda, E. americana, Welwitschia mirabilis) were investigated by TEM and SEM with respect to their anther tapetum and pollen development. In all three species pollenkitt is lacking. The pretended pollen stickiness thus does not depend on pollenkitt. Considering former observations one can now clearly state that pollenkitt is missing in all recent gymnosperm classes (both anemophilous and ± entomophilous). Pollenkitt thus is restricted and ± omnipresent within the angiosperms, where it represents one of the most important components of the entomophily syndrome. This can be regarded as important proof for the hypothesis that the angiosperms are a single coherent phylogenetic group. Keywords: Gymnosperms, Gnetatae, Ephedra, Welwitschia, Pollen, anther, tapetum, pollination ecology, pollenkitt, entomophily, anemophily, origin of angiosperms.
Plant Systematics and Evolution