The prickly rhubarb family also includes the giant rhubarb and it is not actually related to rhubarb
Despite being known as 'giant rhubarb' the Gunnera Manicata leaf isn't edible
The slightly smaller, but similar Gunnera tinctoria from central Chile, has leaves which are edible - just. This too is a remarkable plant. In 1834, Darwin described Gunnera tinctoria (then known as Gunnera scabra)as a plant with “... a very noble appearance”. Both species achieved Awards of Garden Merit: Gunnera manicata in 1993, and Gunnera tinctoria in 2006.
Gunnera possesses glands that contain a cyanobacterium, Nostoc, which fixes nitrogen for the plant, meaning that Gunnera can live in what most plants would consider poor conditions. In fact, Gunnera is the only flowering plant in the world that has a symbiotic relationship with a cyanobacterium (all other nitrogen-fixing plant relationships are with the eukaryotic so-called “true” bacteria rather than prokaryotic cyanobacteria), making the plant of intense interest to molecular botanists. Gunnera is also of interest to indigenous peoples of the Chilean and Peruvian Andes; they eat the tender young stalks and leaves of the plant, called ‘nalcas’ in Spanish.Native to southern Chile, Gunnera tinctoria was first brought to Ireland in 1939 as an ornamental plant. Its popularity as a garden plant grew quickly, and the plant did well since it was growing in a climate similar to its southern hemisphere home. However, despite the similarities of climatic conditions, it was growing in a community of completely different plants without its natural competitors and predators. It began to spread, and now Gunnera tinctoria is found on western Ireland’s coastal cliffs, waterways, roadsides, wet meadows and derelict gardens and fields. Propagating both by seed and by vegetative means, in early spring its leaves begin to grow and in just weeks can reach over 2 meters in height, shading all plants growing below its 2 meter wide leaves. Gunnera tinctoria is now a major threat to plant biodiversity in some areas of Ireland, because smaller plants cannot grow in the shadow created by the giant leaves. To fight the spread of this plant, Ireland is now applying herbicides to get rid of it. Bad news indeed.