Some artificial genera (Fagaceae, Platanaceae, Araliaceae) of Upper Cretaceous of the Northern Hemisphere and heterophylly in some modern hybrids

Abstract

Pedate or three - pieced leaves of Upper Cretaceous angiosperm genera of Europe and North America, Dewalquea, Araliophyllum, Araliopsis and Proteophyllum are investigated for their cuticles. Most of the European samples yielded only one epidermis type pointing to Fagaceae (Castanopsis, Pasania), which is confirmed by fine venation. Some specimens of the Czech Cenomanian seem to have belonged to Araliaceae (Oreopanax). In addition, the leaf morphology in question is common in several remains of Platanaceae with comparable cuticles. In view of the phylogeny, Platanaceae and Fagaceae families are closely related. Heterophylly in Lianas and some modern hybrids of Ranunculaceae, Oleaceae and Fagaceae suggests that an apparent irregular leaf growth predominated during Cretaceous resembling pteridosperms or ferns. In modern counterparts in the cotyledonary regions and bud scales similar patterns are seen. The apparent unusual leaf growth is caused by atavistic accelerated meristem growth at the leaf bases and the margins. It is concluded that long or dwarf shoot growth and timbers occured during Cretaceous. It has been concluded that most of simple leaves of Tertiary and Present time must have been derived from the pedale type of Cretaceous.