![]() ![]() ![]() tinctoria, the inflorescence is club-like with fat, rigid branchlets, and in G. The most distinctive difference between these two species is in the form of the inflorescence. The Gunnera are perennial rhizomatous plants with extremely long petioles (up to 2 m in length) and massive rhubarb-like leaves almost 2 m in width (Figure 1). The most diverse of these, in range and size of individuals, is the subgenus Panke, which includes the two large species G. ) Gunnera is often divided into six subgenera, comprising approximately 45 species (Jarzen 1980). (However, this classification is not always clear and has led some authorities to place these species in a separate family called the Gunneraceae. Most botanists (Heywood 1978, Palkovic 1974) have classified the genus Gunnera in the family Haloragaceae largely a group of submerged aquatic plants. This symbiotic relationship may have important evolutionary significance in the colonization of land by plants, given that Gunnera are among the oldest of angiosperm genera and the only angiosperm genus known to form a symbiotic association with a nitrogen-fixing cyanobacterium. Puzzling aspects of the symbiosis and nitrogen fixation are being explored. tinctoria indicate that the plant is highly dependent on the cyanobacterium Nostoc punctiforme to meet its nitrogen needs. tinctoria has since escaped cultivation and is now well naturalized in western Ireland, and isolated plants also have been found in southwestern Britain and on the Channel Islands. Two giant, herbaceous species, Gunnera tinctoria (or Gunnera scabra) and Gunnera manicata (or Gunnera braziliensis), now grace the edges of lakes and streams in gardens and parks throughout the world, thanks to Victorian plant collectors who brought them back from South America during the nineteenth century. ![]()
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