CO2-fixation Sites in Leaves of Maize and Oats

The primary site of photosynthetic carbon dioxide fixation was determined in the leaves of two monocot species by means of microautoradiographic techniques. Carbon fixation occurred primarily in the vascular-bundle sheath cells in maize whereas fixation in oat occurred uniformly throughout the leaf. The evidence presented suggests that the bundle sheath cells of maize fix carbon via the C.4 dicarboxylic acid pathway.