Structure and relationships of basal relictual angiosperms

Abstract

A review of the present perspective of basal angiosperms and the steps that led to this perspective is provided. Major steps of progress over the past century can be seen with the discovery of new extant plants (Degeneria), new fossils and the advent of new research methods, especially molecular cladistic studies, which catalysed new waves of research. A spectacular result in 1999 was the identification of the well-supported basalmost clades of the angiosperms, forming the ANITA grade, with Amborella, Nymphaeales and Austrobaileyales, by several research groups. This provided a new framework in which basal angiosperms can be discussed in evolutionary terms. In this review basalmost angiosperms (ANITA grade and Chloranthaceae) and other basal angiosperms (eumagnoliids and Ceratophyllaceae) are addressed, with a focus on the different major clades and on general traits and evolutionary tendencies. A short outlook for future avenues is also provided.