Common Name: Wild Rhubarb

General Information

Gunnera perpensa is a perennial herb up to 1 metre tall, growing from a more or less elongated, usually creeping rhizome that is up to 3 cm[].
The plant is harvested from the wild for local use as a food and a medicine[]. A popular medicine in S. Africa, where the plant is predominantly collected from the wild and is sold in markets, pharmacies and supermarkets with a high market value[]. The plant also has potential for use in soil stabilization and restoration projects[].
The population of Gunnera perpensa in S. Africa is declining due to destructive over-harvesting and destruction of its wetland habitats. The plant has become seriously endangered in South Africa, therefore cultivation trials have been carried out in the country[]. This is, however, a widespread species that is found throughout Sub-Saharan Africa and, globally, the plant is classified as 'Least Concern' in the IUCN Red List of Threatened Species(2018)[].

Known Hazards

None known

Botanical References

Range

Eastern Africa - Sudan and Ethiopia south through eastern DR Congo and Tanzania to S. Africa and Madagascar.

Habitat

Swamps, on damp cool ground and in grass by streams; upland forest level; at elevations from 1,500 - 3,800 metres[].

Properties

Conservation Status	Least Concern
Edibility Rating
Medicinal Rating
Habit	Perennial
Height	0.45 m
Pollinators	Wind
Cultivation Status	Cultivated, Wild

Cultivation Details

Although it can grow at quite high elevations in the tropics, this species cannot tolerate frost and even when growing in warm protective areas it will die back for the coldest months of the year[].
Grows in the wild in wet soil or shallow water[]. An obligate wetland plant, it grows in shallow water around the edge of pools in marshy areas or along streams[].
The top part of the inflorescence is male, the bottom is female and the middle is hermaphrodite[].
Members of this genus are rarely if ever troubled by browsing deer[].
It is believed that species of the genus Gunnera have existed for about 95 million years[].
Gunnera species are unique in the plant realm through having a symbiotic relationship with a cyanobacteria (Nostoc punctiforme and others). This relationship provides nitrogen to the Gunnera and carbon to the cyanobacteria[]. The genus Nostoc is cosmopolitan and common, so it is likely to be naturally present in the wet habitats in which Gunnera grows[, ].

Edible Uses

Leaves - chewed or cooked[].
Leaf stems and flower stalks - raw[, ]. The petioles have a bitter taste unless the fibrous vascular bundles and the outer covering are removed[].

The plant (part not specified but likely to be the petiole) is cooked and eaten as a vegetable[].
The plant is an ingredient in traditional beer[].

Medicinal

A decoction of the roots is used to treat dyspepsia, male impotence; to help expel the placenta after birth; and to relieve menstrual pains[, ]. The decoction, in brandy, is used to treat kidney problems[].
An infusion of the root has been taken both internally and externally as a treatment for psoriasis[].
The root has been used to make a dressing for wounds[].

The leaves, rhizomes roots and stems of this species are widely used in traditional medicine in southern Africa. Some uses include relieving pains such as headaches and menstrual cramps; helping in childbirth and stimulating milk production; as well as treating infections and parasites; colds, infertility, cancer and heart disease[].

Studies have shown that extracts of this plant are potentially anthelmintic, antibacterial, antifungal, antiinflammatory, antioxidant, antitumour, lactogenic, and uterotonic although long term use may have detrimental effects such as diarrhoea and leg paralysis[].In traditional medicines a decoction of the plant is used to remove excess fluid from the body or excess blood and the placenta in humans and cattle[].

The plant is rich in tannins.

Agroforestry Uses:

Gunnera species have a high potential for use in the recovery of lands affected by erosion, given their condition as colonizing plants that are capable of fixing atmospheric nitrogen through symbiosis with the cyanobacterium Nostoc punctiform[].

Other Uses

None known

Propagation

Seed - best sown as soon as soon as it is ripe in the autumn in a sandy mix in a cold frame[]. The seed can also be sown in the spring[]. When they are large enough to handle, prick the seedlings out into individual pots and grow them on in the greenhouse for at least their first winter. Plant them out into their permanent positions in late spring or early summer, after the last expected frosts.
Division as new growth commences in the spring[]. Larger clumps can be replanted direct into their permanent positions, though it is best to pot up smaller clumps and grow them on in a cold frame until they are rooting well. Plant them out in the spring.