We quantified the frequency and seasonal variation of ant-plant associations mediated by plant-derived food sources, and the intensity of their use by ants. Thirteen ant species and 42 plant species were related in 135 pairs of associations. The plant families Leguminosae and the Cactaceae were those most visited by ants. The ants Camponotus rubrithorax (28 species) and Crematogaster opaca (16 species) used the most plant species as food sources. No obligatory ant-plant associations were found. Ant species studied did not use all food resources available to them, resulting in a significant differential choice of food resources; using nectar from plant reproductive structures and floral nectar more and extrafloral nectar less. Ant-plant asociations were more frequent during the warm, humid months, when weather conditions are milder, most plants are producing new vegetative growth, many are in flower or fruit and other insects increase their activities. Thus, ants can diversify their foraging activities. Ants are less active during the coldest and driest time of the year. The generalized linear model fitted to the ant-plant interactions curve explained 80% of the variation. This variation is explained by temperature alone; precipitation and the interaction of the two factors were not significant.