is a genus comprising 40 - 50 species of flowering plants and the sole member in family Gunneraceae, native to South America. The genus was named after Johann Ernst Gunnerus (1718 - 23 Sept 1773), a Norwegian bishop and botanist.
(Giant Rhubarb) is native to Serra do Mar mountains in southeastern Brazil, and is one of the largest species. It has large leaves of 1.5 - 2 m wide, and up to 3.4 m long, borne on thick succulent leaf stalk of up to 2.5 m long. The underside of the leaf and the whole stalk have spikes on them. It is not a plant for small garden but if you have the space and the soil is moist, this is a handsome plant. It bears a mass of tiny, red-green flowers that form dense, erect panicles up to 1 m or more long. This plant grows best in damp conditions, such as by the side of garden ponds, but it dislike winter cold and wet. Although it will look rather messy, do not tidy up the dead leaves. Cover the plant with its own dead foliage to protect the crown in winter.
If you really want to plant Gunnera in your garden, plant Gunnera magellanica
, which grows to 15 x 30 cm high and across. It has the same scalloped, dark green leaves of 8 cm across, which are borne on upright stems of up to 15 cm long. The flower spike is rarely be longer than 12 cm long. It is a useful groundcover plant.
Gunnera species grow well in sun or partial shade, in fertile and reliably moist soil. Propagation is by ripe seed; basal cuttings of established plants in spring. Slugs and snails are pests that affect the plants.