Gnetum buchholzianum aka Jointfir

Gnetum buchholzianum is a woody vine that stays green year-round. It belongs to the Gnetaceae family. Names include jointfir, eru, okok and ukasi. Its home range spans Nigeria and west-central tropical Africa. It reaches the Central African Republic and runs south to Congo. It grows beneath trees in warm, damp rainforests. It also grows in young forests and on disused farmland.

The vine grows fast from a rootstock with tubers. Its stems twine to about 33 feet [10 metres], sometimes more. PFAF gives a spread of about 1.3 feet [0.4 metres]. The branches have swollen joints, called nodes. Dark green leaves grow in pairs on opposite sides. Each narrow, oval leaf has a round base. Four to eight pairs of veins curve sharply through each leaf. Shoots from the base bear small leaves like scales. These shoots grow toward the light. Side shoots higher up bear full-sized leaves. The plant cannot set seed through self-fertilisation.

This vine needs a warm, damp site and climbing support. Growers can use a tree to support it. It grows best with about 118 inches of rain yearly. Shade with spots of light beneath trees suits it well. Full sun leads to thinner leaves that buyers value less. It prefers moist soil that drains well. It can grow in sand, loam or clay. Soils can be slightly acid, neutral or slightly alkaline. PFAF lists USDA hardiness zones 10–12. Growers can start plants from cuttings. Seeds can be hard to sprout in nurseries. Wild plants can seed themselves.

People value the leaves as food in parts of Africa. They eat them raw, cook them or add them to sauces. They often shred the tough leaves for soups and condiments. They dry leaves to store them for later use. The leaves provide protein, essential amino acids and minerals. Cut leafy stems stay fresh for at least a week. People also eat the tubers, fruits and seeds. PFAF lists sap as edible, too. Both sources report no known hazards. Neither gives a detailed safety review.

In folk medicine, people use leaves for several health complaints. These include constipation, sore throats, nausea, piles and high blood pressure. People put chopped leaves on boils and warts. They also use a stem infusion during childbirth. These records show past uses, not proof that treatments work. The strong stems bend well. People use them as rope, carrying straps and animal traps. Wild leaf harvest feeds local trade and markets abroad. Heavy harvest has cut wild plant numbers. This has led to trials of growing it for sale. Useful Tropical Plants reports a 2011 assessment of Near Threatened.