Ephedra L. , the sole genus with 65 species. Some species the source of the alkaloid ephedrine . Gnetaceae Shrubs, climbers, or small trees of the Old and New World tropics. Leaves often broad, resembling those of Angiosperms. Gnetum L. , with 28 species.
Some species are sources of fiber, edible leaves and seeds.
Vinkiella R. Johns. , monotypic genus of western New Guinea. Welwitschiaceae Plants consist of a short stout stem and long taproot , the two leaves strap-like, growing through the activity of basal meristems. In the past , the similarities between the reproductive structures of the Gnetales and those of angiosperms have led some authors to suggest the Gnetales as the sister group of the angiosperms. This is the so-called anthophyte theory of the origin of flowering plants. Recently, however, molecular evidence has been obtained indicating that such an origin is unlikely, notably as described in a 1999 commentary by M. W. Frohlich , as well as in the research report by Winter et al.