MORPHOLOGY, ULTRASTRUCTURE AND EVOLUTIONARY SIGNIFICANCE OF MONOSULCATE POLLEN

Data on pollen wall development of a variety of major taxa was examined to help establish homologies among different types of pollen walls and to contribute to understanding evolutionary trends in pollen wall ontogeny. Comparative morphological and ultrastructural studies of monosulcate pollen were also conducted to determine evolutionary trends in pollen wall structure of major extant angiosperm taxa. A number of Mesozoic dispersed saccate and non-saccate pollen were also examined ultrastructurally. The value of the dispersed Mesozoic pollen record in clarifying angiosperm origin(s) and radiation is discussed against the background of these data.