As our cover video illustrates, plant cells are very dynamic; their structure and molecular composition constantly changes as they progress through the cell cycle, divide, differentiate into specialised cell types, and respond to fluctuating environments. Progress in all of these areas is summarized in this issue. Research to characterize the changing molecular composition of cells has gained tremendous momentum in recent years, capitalizing on a combination of well-established model systems and powerful new experimental approaches. Much of the research to date has been specimen collecting — an essential exercise in accumulating examples of genes and understanding the range and types of gene functions. This work is far from finished; at least a third of plant gene functions remain unknown (MASC report 2010; http://www.arabidopsis.org/portals/masc/masc_docs/masc_reports.jsp) and our functional understanding of the remainder is far from complete. This issue includes important new molecular components from many stages of a plant cell's life (mitosis, meiosis, asymmetric cell division, endoreduplication, and differentiation). There are also new insights into many of the cells most important structures (vesicles, the actin cytoskeleton, plasmodesmata, and the cell wall). It seems as if we are getting closer to a more complete molecular description of the main components of plant cells.