Reconsiderations on two characters of early angiosperm Archaefructus

Abstract

Archaefructus is a genus of considerable interest and importance in the study of early angiosperms. Three previously documented species have provided important information about early angiosperms, although some of their characters have been interpreted in various ways. Additional new materials presented in this paper along with the holotype of Archaefructus liaoningensis illustrate branching pattern, fruit arrangement, and seed attachment in Archaefructus. New observations indicate that Archaefructus has ovules/seeds attached to the midrib on the abaxial side of the fruits and a whorled/opposite arrangement for the fruits on the axis. New fossil material of Archaefructus sinensis demonstrates that fruit pairs are inserted on the infructescence axis oppositely. The diagnoses of Archaefructus and Archaefructaceae are emended, and their significance on early angiosperm evolution is discussed.