Gnetophyta

The division Gnetophyta has three families across three orders: Ephedraceae, Gnetaceae, and Welwitschiaceae. The family Ephedraceae consists of about 65 species of shrubs in a single genus, Ephedra. Gnetaceae has some 30 species in the genus Gnetum, many of which are trees or vines. Welwitschiaceae consists of a single species, Welwitschia mirabilis, characterized by a massive squat stem and two leaves.

Some Ephedra species may have both microstrobili and megastrobili on the same plant, though they more commonly occur on separate plants. Both Gnetum and Welwitschia are dioecious.

The large oval leaves of Gnetum look much like those of dicotyledonous angiosperms, while those of Ephedra are small and scalelike. The two leaves of Welwitschia are leathery and straplike and survive for the life of the plant.

Neither Ephedra nor Gnetum produce extensive vascular cylinders, though Gnetum, unlike most gymnosperms, has vessels in the xylem.