Nuphar lutea
Interestingly, flower and rhizome formation in genus "Nuphar" has come under recent electron microscope study by phylogenetic researchers, on the assumption that the very first angiosperms—which have left no trace in the fossil record – share many of the unique characteristics of the basal genus of which "Nuphar lutea" is a part. Russian biologists are foremost in these efforts, exploring the "golden spiral" formation of the rhizome and the whorl mechanism by which flower parts develop—this photograph capturing a "Nuphar lutea" Gynoecium at a late stage in flower development, “pe” for petal and “s5” for one of its five sepals.