Pollen Morphology and Plant Taxonomy of Red Oaks in Eastern North America
American Journal of Botany 70(4): 495-507
ISSN/ISBN: 0002-9122 DOI: 10.1002/j.1537-2197.1983.tb07877.x
Identification of Quercus (oak) pollen taxa could enhance Quaternary palynological interpretations from eastern North America. A first step is to determine a morphological and taxonomic basis for such identifications. Scanning electron microscopy was utilized to examine exine-surface features of 266 specimens representing 21 red oak (subgenus Erythrobalanus) species from eastern North America, and 2 intermediate oak (subgenus Protobalanus) species from the desert southwest. Twenty pollen morphological characteristics defined previously were tabulated for each of 324 pollen grains. The data were subjected to cluster analyses. Cluster diagrams were compared with traditional oak systematics. Pollen morphology and plant taxonomy compared poorly with respect to series and species relationships among the red oaks, apparently due as much to high intraspecific and low interspecific variability in pollen-morphological characters as to the uncertain taxonomy of red oaks. Pollen morphology does support the hypothesis of subgeneric oak evolution from intermediate oaks to the series Virentes of white oaks and from more advanced white oaks to the red oak species.