Phylogenetic interrelationships in the enlarged order Ericales were investigated by jackknife analysis of a combination of DNA sequences from the plastid genes rbcL, ndhF, atpB, and the mitochondrial genes atp1 and matR. Several well-supported groups were identified, but neither a combination of all gene sequences nor any one alone fully resolved the relationships between all major clades in Ericales. All investigated families except Theaceae were found to be monophyletic. Four families, Marcgraviaceae, Balsaminaceae, Pellicieraceae, and Tetrameristaceae form a monophyletic group that is the sister of the remaining families. On the next higher level, Fouquieriaceae and Polemoniaceae form a clade that is sister to the majority of families that form a group with eight supported clades between which the interrelationships are unresolved: Theaceae-Ternstroemioideae with Ficalhoa, Sladenia, and Pentaphylacaceae; Theaceae-Theoideae; Ebenaceae and Lissocarpaceae; Symplocaceae; Maesaceae, Theophrastaceae, Primulaceae, and Myrsinaceae; Styracaceae and Diapensiaceae; Lecythidaceae and Sapotaceae; Actinidiaceae, Roridulaceae, Sarraceniaceae, Clethraceae, Cyrillaceae, and Ericaceae.

Gnetales comprise three unusual genera of seed plants, Ephedra, Gnetum, and Welwitschia. Their extraordinary morphological diversity suggests that they are survivors of an ancient, more diverse group. Gnetalean antiquity is also supported by fossil data. Dispersed ''ephedroid'' (polyplicate) pollen first appeared in the Permian >250 million years ago (Myr), and a few megafossils document the presence of gnetalean features in the early Cretaceous. The Cretaceous welwitschioid seedling Cratonia cotyledon dates the split between Gnetum and Welwitschia to before 110 Myr. Ages and character evolution of modern diversity are, however, controversial, and, based on molecular data, it has recently been suggested that Ephedra is very young, only 8 -32 Myr. Here, we present data on the evolutionary history of Ephedra. Fossil seeds from Buarcos, Portugal, unequivocally link one type of Cretaceous polyplicate pollen to Ephedra and document that plants with unique characters, including the peculiar naked male gametophyte, were established already in the Early Cretaceous. Clades in our molecular phylogeny of extant species correspond to geographical regions, with African species in a basal grade͞clade. The study demonstrates extremely low divergence in both molecular and morphological characters in Ephedra. Features observed in the fossils are present in all major extant clades, showing that modern species have retained unique reproductive characters for >110 million years. A recent origin of modern species of Ephedra would imply that the Cretaceous Ephedra fossils discussed here were members of widespread, now extinct sister lineage(s), and that no morphological innovations characterized the second diversification. molecular phylogeny ͉ fossil record ͉ Gnetales ͉ molecular dating

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