Laboratory measurements of the uptake of COS by soybeans, corn, wheat, and alfalfa under conditions of controlled illumination, temperature, and CO2 concentration, and at COS concentrations spanning those typically found in the troposphere (~500 parts per trillion by volume), indicate that the major uptake pathway is through open stomata. Similarities between the uptake resistances observed for COS and CO2 provide a means of estimating global COS uptake from estimates of global terrestrial primary plant productivity. With an estimated annual plant uptake of 0.2--0.6 Tg COS (Tg=1012 g), this appears to be the largest global sink for this major tropospheric sulfur reservoir species. With this vegetative sink included, estimated known sources and sinks appear to be in approximate balance. ¿ American Geophysical Union 1988