Angiosperm embryology in the 21st century: Reflections

During the 20th century significant advances have been made in developmental and comparative embryology and its role in taxonomic considerations. However, the causes for variations in spindle organization during microsporogenesis, pollen structure in Cyperaceae and Epacridaceae, pollen bud development in some members of Rubiaceae, pollen embryo sacs in Hyacinthus, differential organization of the four megaspore nuclei in coenomegaspore, variations in development of embryo sacs, embryo and endosperm are not fully understood. These and other related features should be investigated during the 21st century.