Gunnera tinctoria: An Unusual Nitrogen-fixing InvaderThis water-loving species may offer insights into the development of terrestrial plants

toria indicate that the plant is highly dependent on the cyanobacterium Nostoc punctiforme to meet its nitrogen needs. Puzzling aspects of the symbiosis and nitrogen fixation are being explored. 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.