|Marilyn chasing emu eating plants, 2009
|C-3 and C-4 plants have distinct isotope compositions
C-3 and C-4 Plants
Another set of plants turn the carbon dioxide in air into a 4-carbon sugar and so we call them C-4 plants (C4). C4 plants evolved well after C-3 plants and this adaptation allows them to thrive in hot, dry environments, such as the outback of Australia. C4 plants absorb the lighter carbon-12 isotope significantly slower than the C3 plants, because the protein that uses the carbon dioxide works differently. Because these proteins in plants that take up carbon dioxide are different, their carbon isotopes are different as well. Scientists now use these differences to determine whether a plant is a C-3 or C-plant.
|The shrubs in the photo--chenopods-have isotope signals between C-3 and C-4 plants. Emus eat their flowers and seeds.