How does reproduction in Gnetum differ from reproduction in Ephedra?

Reproduction in Gnetum and Ephedra differs in several key structural and developmental aspects:

• Strobili Arrangement: In Ephedra, reproductive structures are produced in compound strobili. In contrast, the strobili of Gnetum are borne in a series of whorls on elongated axes, which are sometimes referred to as "inflorescences".12
• Presence of Archegonia: A significant difference lies in the female gametophyte. Ephedra produces archegonia—protective structures that contain the egg cells. Gnetum, however, does not form archegonia; only egg cells occur within its female gametophytes.132
• Timing of Fertilization: In Gnetum, fertilization occurs before the female gametophyte becomes completely cellular. In Ephedra, the female gametophyte typically undergoes extensive nuclear division to become a cellular structure before the formation of archegonia and subsequent fertilization.23

While both genera are members of the Gnetophyta and share certain traits—such as having two integuments on their ovules and lacking flagellated sperm—these distinctions in their reproductive development highlight the evolutionary diversity within the group.1