Gnetum is a genus of
gymnosperms, the sole genus in the family
Gnetaceae and order
Gnetales. They are
tropical evergreen trees,
shrubs and
lianas. Unlike other gymnosperms they possess
vessel elements in the
xylem. Some species have been proposed to have been the first plants to be insect pollinated as their fossils occur in association with the extinct pollinating
scorpionflies. Molecular phylogenies based on nuclear and plastid sequences from most of the species indicate hybridization among some of the Southeast Asian species. Fossil-calibrated molecular-clocks suggest that the
Gnetum lineages now found in Africa, South America, and Southeast Asia are the result of ancient long-distance dispersal across seawater.