title: Morphology and affinities of an Early Cretaceous Ephedra (Ephedraceae) from China.
abstract: Detailed investigations on Lower Cretaceous Ephedra L. fossils (Gnetopsida) reveal morphological characters similar to those of extant Ephedra rhytidosperma Pachomova, including articulate branches with many fine longitudinal striations, a dichasial branching pattern, uni- or bi-ovulate cones with paired bracts, cones terminal on branchlets, and seeds with a short, straight micropylar tubes, covered by numerous regular and prominent transverse laminar protuberances. Fossils are similar to extant E. rhytidosperma reproductive organs but differ in some vegetative structures and are described and discussed here as Ephedra archaeorhytidosperma Y. Yang et al. Because E. rhytidosperma is currently considered one of the most specialized members in Ephedra L. section Pseudobaccatae Stapf, the occurrence of E. archaeorhytidosperma in the Yixian Formation suggests that Ephedra L. was perhaps a more diverse genus in the Lower Cretaceous. Perhaps the evolution and diversity of Ephedra L. was already in place by the Lower Cretaceous and certainly before the end of the Mesozoic.
authors.affiliation: Laboratory of Systematic and Evolutionary Botany, and Herbarium, Institute of Botany, the Chinese Academy of Sciences, Xiangshan, Beijing 100093, People's Republic of China;
authors.forename: Yong
authors.initials: Y
authors.lastname: Yang
authors.forename: Bao-Yin
authors.initials: BY
authors.lastname: Geng
authors.forename: David L
authors.initials: DL
authors.lastname: Dilcher
authors.forename: Zhi-Duan
authors.initials: ZD
authors.lastname: Chen
authors.forename: Terry A
authors.initials: TA
authors.lastname: Lott