|MadSci Network: Botany|
That's an interesting question. If you want the individual plant that gives off the most oxygen each year, it is probably the 43 hectare (106 acre) network of quaking aspen tree trunks ( Populus tremuloides) in Utah that the Guinness Book of World Records lists as the world's largest living organism. The mass of the quaking aspen is estimated at 6 million kg (6,600 tons). The quaking aspen is considered a single organism because all the stems originate from one root system. There was an article in Discover magazine several years ago on the world record quaking aspen.
In terms of the most oxygen produced per unit ground area covered by a single plant species, it would be a tropical grass or other species with C-4 photosynthesis, such as cultivated corn ( Zea mays). For natural ecosystems per unit ground area, tropical rain forests generally have the highest annual rates of photosynthesis.
Salisbury, F.B. and Ross, C.W. 1985. Plant Physiology. Belmont, CA: Wadsworth Publishing.
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