Taken as a whole, Devonian and Carboniferous floras represent vastly different evolutionary stages in the colonization of the Earth's surface by plants. When only Late Devonian and Mississippian floras are considered, however, all of the floral innovations that led to and characterize the increasingly sophisticated plant communities of the Carboniferous began in the Famennian. When examined carefully enough, the stratigraphical succession of floras at the Devonian/Mississippian boundary reveals a gradual decline of typical Late Devonian elements and an equally gradual increase of plant types that eventually characterize the Early Mississippian. Furthermore, significant floral changes occur throughout the Late Devonian as archaic genera, that originated in Middle Devonian or earlier, disappear and new types appear that will become important in the Mississippian. Within the Mississippian too, the earliest floras contain elements left over from the Devonian, but show the origins or expansions of groups that ultimately were of great importance in the Pennsylvanian.