ABSTRACT Cleistocactus baumannii is the only ornithophilous cactus species in the Brazilian Chaco. In addition, this species of Cactaceae invests heavily in flowering in the ecoregion. Such characteristics motivated us to evaluate the temporal availability of flowers in the context of its floral visitors. The reproductive system of C. baumannii, the number of individuals in flowering, flower abundance and the frequency and richness of floral visitors were evaluated and quantified. Nectar robbery was a frequent phenomenon in the studied population; therefore, we compared the pollen load deposited on the stigma of damaged (robbery) and undamaged flowers. In the Brazilian Chaco, C. baumannii is self-incompatible and has a continuous flowering pattern,... |