Sugarcane is a champion at photosynthesis under the right conditions and is a prime example of a C4 plant, one which uses C4 photosynthesis. Sugarcane has been recorded at 7% .
The drawback to C4 photosynthesis is the extra energy in the form of that is used to pump the 4-carbon acids to the bundle sheath cell and the pumping of the 3-carbon compound back to the mesophyll cell for conversion to PEP. This loss to the system is why C3 plants will outperform C4 plants if there is a lot of water and sun. The C4 plants make some of that energy back in the fact that the rubisco is optimally used and the plant has to spend less energy synthesizing rubisco.
C3 plants have the disadvantage that in hot dry conditions their photosynthetic efficiency suffers because of a process called . When the CO2 concentration in the drops below about 50 ppm, the catalyst that helps to fix carbon begins to fix oxygen instead. This is highly wasteful of the energy that has been collected from the light, and causes the rubisco to operate at perhaps a quarter of its maximal rate.
Moore, et al. point to Flaveria (Asteraceae), Panicum (Poaceae) and Alternanthera (Amarantheceae) as genera that contain species that are intermediates between C3 and C4 photosynthesis. These plants have intermediate leaf anatomies that contain bundle sheath cells that are less distinct and developed than the .
PETERSON/ECHS Describe the light reactions of photosynthesis and, for both a C3 and a C4 plant, trace the path of a carbon dioxide molecule from the point at which it enters a plant to its incorporation into a glucose molecule.