Morphologicals evolution of pteridophytic spores in relation to free-floating environment

Abstract

The free-floating ferns are mostly herbaceous with a trilete mark on the spores. They first evolved in the Early Cretaceous, radiated in the Late Cretaceous and except for Azolla and Salvinia, all of them died out by the Late-Maestrichtian. The common genera are: Arecellites, Molaspora, Balmaeisporites, Ariadnaesporites, Glomerisporites, Parazolla, Azollopsis, Azolla and Salvini. The morphological evolution and adaptation of these genera in relation to the free floating environment is discussed.