Gunnera Manicata Growing At Marble Hill
Just down the lane and round the corner from the main house there is an almost prehistoric looking plant that raises its head in the spring growing to nearly 3 metres high in the summer, spreading across nearly 4 metres. This is the magnificent Gunnera or to give it its more common name Chilean rhubarb, or Brazilian rhubarb. The Gunnera here has been planted in a hollow; and benefits from the large amount of leaf mound in the area which has afforded it the best protection from any frosts allowing it to develop into this fantastic specimen. We are not the only ones who think this to be a rather special plant in fact The Royal Horticultural Society has given it its Award of Garden Merit.
The Gunnera genus contains about 50 different types and has a variety of both leaf shapes and sizes.
The Gunnera here at Marble Hill is Gunnera manicata which is one of the giant versions of this genus. Native to the Serra do Mar mountains of south eastern Brazil it adores the Irish climate revelling in the moist humidity.
In nature, all Gunnera plants form a symbiosis with nitrogen-fixing cyanobacteria, thought to be exclusively Nostoc punctiforme. The bacteria enter the plant via glands found at the base of each leaf stalk and initiate an intracellular symbiosis which is thought to provide the plant with fixed nitrogen in return for fixed carbon for the bacterium. This intracellular interaction is unique in flowering plants and may provide insights to allow the creation of novel symbioses between crop plants and cyanobacteria, allowing growth in areas lacking fixed nitrogen in the soil.
This species is named after the Norwegian botanist and Bishop Johann Ernst Gunnerus (1718 – 23 September 1773).