Gnetum

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Gnetum is a genus of gymnosperms in the family Gnetaceae, within the group Gnetophyta. They are tropical evergreen trees, shrubs, and climbing plants (lianas). A distinctive feature is that, unlike most gymnosperms, Gnetum has vessel elements in its xylem.

There are over 50 species, with the Catalogue of Life listing around 44. Many Gnetum species are edible: the seeds can be roasted, and the leaves are used as a leafy vegetable; the plants also yield fiber.

Fossil evidence suggests some ancient Gnetum may have been insect-pollinated, linked to extinct pollinating scorpionflies. Molecular studies indicate that some Southeast Asian species have hybridized. Molecular clocks suggest the Gnetum lineages now found in Africa, South America, and Southeast Asia spread to their current regions through ancient long-distance dispersal across seawater.

Leaves are rich in phytochemicals such as flavonoids and stilbenes. The family is known for stilbenoids, compounds with potential health effects; some studies point to anti-coagulation effects from stilbenoids.

Gnetum plants have lower photosynthetic and transpiration rates than many other seed plants, due in part to the absence of several chloroplast genes for photosynthesis. This trait is shared with other living Gnetophyta members like Ephedra and Welwitschia, as well as conifers.

Conservation: some species are endangered as tropical rainforests are cleared for industry and farmland. Habitat loss threatens many Gnetum species, including Gnetum oxycarpum, which faces significant risk.