Evidence for and Implications of an Herbaceous Origin for Angiosperms

Abstract

For over a century, botanists have speculated on the ancestral morphology of the angiosperms and on the adaptive characteristics that led to their success. Most discussions have centered on the ancestral form of the flower and associated organs. At present, there are two major alternative views regarding the morphology of the first angiosperm. The first of these, which we term the Magnolialean hypothesis, is concordant with the Anthostrobilus or Euanthial floral hypothesis (Fig. 8.1) of Arber and Parkin (1907) and pictures early angiosperms as having been woody shrubs or small trees with large, complex, multiparted flowers. Living species regarded as similar to the archetype are members of the winteroids and Magnoliales (Fig. 11.1 and 11.2). The second view parallels the Pseudanthial hypothesis (Fig. 8.1) of Wettstein (1907a). In this formulation, the ancestral angiosperm is perceived as a rhizomatous herb with small, simple flowers as in living herbaceous magnoliids such as Chloranthaceae and Piperaceae.