The objective of the Leaf Photosynthesis study was to measure the response of leaf photosynthesis and stomatal conductance to light, temperature, vapor pressure deficit, carbon dioxide and water potential for the most abundant C4 species at the FIFE study area. To this end, photosynthesis measurements were made on 6 days in June, July and August of 1987 at three different locations in the northwest quadrant of the FIFE study area. Leaf photosynthetic rate is measured by enclosing a leaf in a closed, transparent chamber and measuring the decrease in carbon dioxide concentration as a function of time. Light flux density is measured outside of the chamber and must be corrected for the chamber transmittance, which is 0.9. These data can be fit to various models of leaf photosynthesis and stomatal conductance by providing the responses to light, temperature leaf water potential, and carbon dioxide under field conditions on intact plants.