The Cretaceous was a time of profound global change in floral composition and vegetation structure, both temporally and spatially.
Early Cretaceous vegetation and rates of species turnover were generally similar to those of the Jurassic. At low latitudes the Cheirolepidiaceae (Classopollis producers) and bennettites characterized arid and semi-arid belts, forming savanna-type vegetation with fern ground cover and cycadophyte shrubs. Primary elements in riparian and disturbed sites were ferns and cycadophytes; on floodplains were sphenopsids, lycopods, and ferns; while backswamps were dominated by “leafy” conifers. Conifer forests with an understory of ferns, ginkgophytes, and Czekanowskiales were the major coal-formers and were prevalent at higher (humid) latitudes.
The middle Cretaceous saw the initial diversification of the angiosperms as an early successional component of the vegetation, particularly in stream margins and disturbed sites. Most angiosperm physiognomic foliage types had evolved by the end of the Cenomanian. Globally forests remained dominated by conifers. Czekanowskiales, Gink-goales, and Podozamites persisted at higher latitudes before declining due to (angiosperm?) competition and climatic deterioration. Brachyphyllous conifers were widespread at middle latitudes.
During the late Cretaceous angiosperm radiation, groups that previously dominated arid belts (e.g., Cheirolepidiaceae) and angiosperm competitors (pteridosperms and cycadophytes) declined, but this period of dynamic vegetational change supported more major plant groups than at any other time. Angiosperm trees and shrubs played an increased role in climax vegetation as well as forming riparian thickets. Most coal-forming communities remained conifer-dominated throughout the Cretaceous and many contain a high proportion of deciduous elements.