Pollen Structure and Development in Ephedra americana (Gnetales)
Allison S. Doores
Dr. Jeffrey M. Osborn, Faculty Mentor
Ephedra americana, or Mormon's Tea, has been used in weight loss and energy boosting supplements, although the US Food and Drug Administration has banned the use of such products. Historically, the Gnetales have been regarded as the sister group to flowering plants, but recent molecular studies have nested the order within the conifers. The objective of this research was to comparatively study pollen ontogeny of Ephedra americana. Using combined light, scanning electron, and transmission electron microscopy, all major developmental stages have been documented, including the microspore mother cell, tetrad, free microspore, and mature stages. Ontogenetic events including the deposition of a callose wall, primexine, and sporoderm layers will be discussed. Significant exine deposition occurs during the tetrad stage. Although mature grains are inaperturate, the exine is considerably thinner within the furrows, which mainly have a straight morphology. These developmental characters will be discussed regarding systematic and phylogenetic interpretations of Ephedra.
Keywords: Ephedra, Gnetales, Pollen, Ontogeny, Development, Morphology, Ultrastructure, Electron microscopy
Presentation Type: Oral Paper
Location: VH 1432