Gunnera

Gunnera is the sole genus of herbaceous flowering plants in the family Gunneraceae, which contains 63 species. Some species have extremely large leaves. Species in the genus are variously native to Latin America, Australia, New Zealand, Papuasia, Hawaii, insular Southeast Asia, Africa, and Madagascar.[2] The stalks of many species are edible.

Gunnera
Gunnera tinctoria at the San Francisco Botanical Garden at Strybing Arboretum
Scientific classification
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Eudicots
Order: Gunnerales
Family: Gunneraceae
Genus: Gunnera
L.
The range of the genus Gunnera[1]
Synonyms[2]
  • Milligania Hook.f., rejected name
  • Panke Molina
  • Pankea Oerst.

Description

The 40–50 species vary enormously in leaf size. The giant rhubarb, or Campos des Loges (Gunnera manicata), native to the Serra do Mar mountains of southeastern Brazil, is perhaps the largest species, with reniform or sub-reniform leaves typically 1.5 to 2.0 meters (4.9 to 6.6 ft) long, not including the thick, succulent petiole which may be up to 2.5 meters (8.2 feet) in length. The width of the leaf blade is typically 2.5 meters (8.2 feet), but on two separate occasions cultivated specimens (In Devon, England in 2011[3] and at Narrowwater, Ulster, Ireland[4] in 1903) produced leaves fully 3.3 meters (11 feet) in width, not far from the largest of all dicot leaves such as Victoria amazonica. The seeds germinate best in very moist, but not wet, conditions and temperatures of 22–29 °C.

Only slightly smaller is G. masafuerae of the Juan Fernandez Islands off the Chilean coast. They can have leaves up to 2.9 m (9 ft 6 in) in width on stout leaf stalks 1.5 m (4.9 ft) long and 11 cm (4.3 in) thick according to Skottsberg.[5] these leafstalks or petioles are the thickest of any dicot, and probably also the most massive. On nearby Isla Más Afuera, G. peltata frequently has an upright trunk to 5.5 m (18 ft) in height by 25–30 cm (9.8–11.8 in) thick, bearing leaves up to 2 m (6 ft 7 in) wide. The Hoja de Pantano (G. magnifica) of the Colombian Andes bears the largest leaf buds of any plant; up to 60 cm (2.0 ft) long and 40 cm (16 in) thick.[6] The succulent leaf stalks are up to 2.7 m (8 ft 10 in) long. The massive inflorescence of small, reddish flowers is up to 2.3 m (7 ft 7 in) long and weighs about 13 kg. Other giant Gunnera species are found throughout the Neotropics and Hawaii. Gunnera insignis is also known by the name "poor man's umbrella" in Costa Rica.

Several small species are found in New Zealand, notably G. albocarpa, with leaves only 1–2 cm long, and also in South America, with G. magellanica having leaves 5–9 cm wide on stalks 8–15 cm long.

Gunnera manicata Devon, England
Gunnera insignis Costa Rica

Taxonomy

The genus Gunnera was named after the Norwegian botanist Johann Ernst Gunnerus. At first it was assigned to the family Haloragaceae, though that presented difficulties that led to the general recognition of the family Gunneraceae, as had been proposed about the beginning of the 20th century. In the meantime in many publications it had been referred to as being in the Haloragaceae, variously misspelt (as for example "Halorrhagidaceae".[7]) Such references still cause difficulties in consulting earlier works. However, currently Gunnera is firmly assigned to the monogeneric family Gunneraceae.[8]

Species[2]
  1. Gunnera aequatoriensis - Ecuador
  2. Gunnera albocarpa - New Zealand
  3. Gunnera annae - Peru, Bolivia
  4. Gunnera antioquensis L.E.Mora - Colombia
  5. Gunnera apiculata - Bolivia, Argentina
  6. Gunnera arenaria - New Zealand
  7. Gunnera atropurpurea - Colombia, Ecuador
  8. Gunnera berteroi - Bolivia, Argentina, Chile
  9. Gunnera bogotana - Colombia
  10. Gunnera bolivari - Peru, Ecuador
  11. Gunnera bracteata - Robinson Crusoe Island in Chile
  12. Gunnera brephogea - Colombia, Ecuador, Peru
  13. Gunnera caucana - Colombia
  14. Gunnera colombiana - Colombia, Ecuador
  15. Gunnera cordifolia - Tasmania
  16. Gunnera cuatrecasasii - Colombia
  17. Gunnera densiflora - New Zealand
  18. Gunnera dentata - New Zealand
  19. Gunnera diazii - Colombia
  20. Gunnera flavida - New Zealand
  21. Gunnera garciae-barrigae - Colombia
  22. Gunnera hamiltonii - New Zealand
  23. Gunnera hernandezii - Colombia
  24. Gunnera herteri Osten - Uruguay, S Brazil
  25. Gunnera insignis - Panama, Nicaragua, Costa Rica
  26. Gunnera kauaiensis - Kauai in Hawaii
  27. Gunnera killipiana - Chiapas, Guatemala, Honduras
  28. Gunnera lobata - Tierra del Fuego
  29. Gunnera lozanoi - Colombia
  30. Gunnera macrophylla - Papuasia, Indonesia, Philippines
  31. Gunnera magellanica - W + S South America, Falkland Is.
  32. Gunnera magnifica - Colombia
  33. Gunnera manicata - S Brazil
  34. Gunnera margaretae - Peru, Bolivia
  35. Gunnera masafuerae - Alejandro Selkirk Island (Isla Mas Afuera) in Chile
  36. Gunnera mexicana - Veracruz, Chiapas
  37. Gunnera mixta - New Zealand
  38. Gunnera monoica - New Zealand incl Chatham Islands
  39. Gunnera morae - Colombia
  40. Gunnera peltata - Robinson Crusoe Island in Chile
  41. Gunnera perpensa - Africa, Madagascar
  42. Gunnera peruviana - Ecuador, Peru
  43. Gunnera petaloidea - Hawaii
  44. Gunnera pilosa - Peru, Bolivia, Ecuador
  45. Gunnera pittieriana - Venezuela
  46. Gunnera prorepens- New Zealand
  47. Gunnera quitoensis - Ecuador
  48. Gunnera reniformis - New Guinea
  49. Gunnera saint-johnii - Colombia
  50. Gunnera sanctae-marthae - Colombia
  51. Gunnera schindleri - Bolivia, Argentina
  52. Gunnera schultesii - Colombia
  53. Gunnera silvioana - Ecuador, Colombia
  54. Gunnera steyermarkii - Venezuela
  55. Gunnera strigosa- New Zealand
  56. Gunnera tacueyana - Colombia
  57. Gunnera tajumbina - Ecuador, Colombia
  58. Gunnera talamancana - Costa Rica, Panama
  59. Gunnera tamanensis - Colombia
  60. Gunnera tayrona - Colombia
  61. Gunnera tinctoria - Chile, Argentina
  62. Gunnera venezolana - Venezuela

Cyanobacterial symbiosis

At least some species of Gunnera host endosymbiotic cyanobacteria such as Nostoc punctiforme. The cyanobacteria provide fixed nitrogen to the plant, while the plant provides fixed carbon to the microbe.[9] The bacteria enter the plant via glands found at the base of each leaf stalk[1] 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.

Uses

The stalks of G. tinctoria (nalcas), from Southern Chile and Argentina, are edible. Their principal use is fresh consumption, but also they are prepared in salads, liquor or marmalade. Leaves of this species are used in covering curanto (a traditional Chilean food).

Gunnera perpensa is a source of traditional medicine in Southern Africa, both in veterinary and human ailments, largely in obstetric and digestive complaints, but also as a wound dressing.[7] It also is eaten in various ways, largely the petioles, flower stalks and leaves, fresh and raw, preferably with skins and fibre removed, which is said to remove bitterness, but also cooked. The plant also is said to be used in making a beer.[10]

References
  1. Bergman, B.; Johansson, C.; Söderbäck, E. (1992). "The Nostoc–Gunnera symbiosis". New Phytologist. 122 (3): 379. doi:10.1111/j.1469-8137.1992.tb00067.x.
  2. Kew World Checklist of Selected Plant Families
  3. "Abbotsbury Gardens celebrates plant's 'monster' leaves". BBC. 14 October 2011.
  4. The Garden (London) Vol. 63 # 1631 (February 21, 1903) p. 125.
  5. Dr Carl Skottsberg, , "The Phanerogams of Juan Fernandez Islands", NATURAL HISTORY OF JUAN FERNANDEZ AND EASTER ISLAND (Uppsala: Almqvist & Wiksells Buktrykeri A.S., 1953) Vol. 2 p.151.
  6. Dr. Harold St. John, "Gunnera the Magnificent - Giant Herb of Colombia", CHICAGO NATURAL HISTORY MUSEUM BULLETIN, Vol. 30 # 1 (January 1959) p. 3 plus photo on front cover.
  7. Watt, John Mitchell; Breyer-Brandwijk, Maria Gerdina: The Medicinal and Poisonous Plants of Southern and Eastern Africa 2nd ed Pub. E & S Livingstone 1962 (Described in chapter on Halorrhagidaceae, p 500)
  8. Wanntorp, L. Wanntorp, H-E. Oxelman, B. Källersjö, M. Phylogeny of Gunnera. Plant Systematics and Evolution Vol. 226, No. 1/2 (March 2001), pp. 85-107
  9. Francis C. Y. Wong and John C. Meek. Establishment of a functional symbiosis between the cyanobacterium Nostoc punctiforme and the bryophyte Anthoceros punctatus requires genes involved in nitrogen control and initiation of heterocyst differentiation. Microbiology (2002), 148, 315-323 [www.microbiologyresearch.org]
  10. Fox, Francis William. Food from the veld. Pub: Delta Books (1982) ISBN 978-0908387328
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