Gnetum

倪藤果 Gnetum gnemon -檳城熱帶果園 Tropical Fruit Farm, Penang- (9222653200)

Gnetum laolium - കറുത്ത ഓടൽ

Gnetum africanum Leaves (Eru, Okok)

Gnetum gnemon seeds, by Omar Hoftun

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. Gnetum species are found in the humid tropics of South America, Africa, and Asia. The genus includes both trees and vines, some of which are used by local populations for food and other purposes.

Description

Gnetum species are characterized by their broad leaves, which resemble those of angiosperms, making them unique among gymnosperms. The leaves are opposite, broad, and flat with a prominent midrib. The plants are dioecious, with male and female cones produced on separate plants. The male cones are small and numerous, while the female cones are larger and contain a single seed each. The seeds of Gnetum are notable for their fleshy and edible outer layer, which is consumed by wildlife and humans in some regions.

Ecology

Gnetum species play a significant role in their ecosystems. They are often found in the understory of tropical forests, where they can be climbers, using other trees for support, or grow as independent trees or shrubs. Their seeds are dispersed by animals, including birds and bats, which feed on the fleshy seed coat.

Uses

Several species of Gnetum are of local economic importance. For example, the leaves of Gnetum africanum and Gnetum buchholzianum are used in West Africa as a vegetable, known as okok, eru, or mfumbua. The seeds of some species are also edible and are used in traditional dishes. Beyond their food value, Gnetum species have been used in traditional medicine and as a source of fiber.

Conservation

The conservation status of Gnetum species varies. Some species are under threat due to habitat destruction, especially from deforestation and agricultural expansion. Conservation efforts are necessary to ensure the survival of these unique gymnosperms, which have important ecological, economic, and cultural values.

Taxonomy

The taxonomy of Gnetum has been a subject of research and debate. It is the only genus in the family Gnetaceae, which is one of the three families in the order Gnetales, alongside Ephedraceae and Welwitschiaceae. This order is significant in the study of plant evolution, as it represents a group of gymnosperms with some characteristics similar to angiosperms.

Phylogeny

The phylogenetic position of Gnetum within the seed plants has been a matter of debate. Molecular studies have provided insights into the relationships between Gnetum, other gymnosperms, and angiosperms, suggesting that Gnetales may be more closely related to conifers than to angiosperms, challenging earlier theories that proposed a closer relationship between Gnetales and angiosperms.