Floodplain lakes and associated wetlands in tropical dry climates are controlled by pronounced and severe seasonal hydrologic fluctuations. We examined the plant community response to a bimodal flooding pattern in the Zapatosa Floodplain Lake Complex (ZFLC), Northern Colombia. We measured floristic and quantitative change in four sampling periods emphasizing seasonal differences in plant abundance and life-form structure. Of 79 species identified in the lake complex, 52 were used to characterize eight community types via classification and ordination procedures. Results showed that community structure does not change significantly during the flooding/receding stages. But maximum drawdown phase significantly disrupts the aquatic community structure and the exposed shorelines become colonized by ruderal terrestrial plants. Early rainfalls at the beginning of the wet season are emphasized as an important feature of plant regeneration and community development. The general strategy of the ZFLC vegetation can be framed into the flood pulse concept of river-floodplain systems. Thus, plant communities are mainly responding to disturbances and destruction events imposed by extreme water level fluctuations. Rev. Biol. Trop. 62 (3): 1073-1097. Epub 2014 September 01.Key words: Cesar River, flood pulse, littoral, macrophytes, Magdalena River, shallow lakes, bimodal seasonality.Floodplains play an important role regarding the biogeochemistry and ecology of tropical river systems. Plant and animal life of this particular system are adapted to the seasonal variations in space and time caused by extreme water level fluctuations. This seasonality also represents an important factor in the speciation of several aquatic and wetland plants (Haynes & Holm-Nielsen, 1989). The dynamic character of these systems gives rise to complex primary and secondary production processes that are difficult to predict in detail, but nutrient input from rivers and streams are important in general, as a significant contribution can be expected following rainfall from the surrounding watershed. Nutrient cycling proceeds mainly through heterotrophic processes via bacteria, fungi, micro-zooplankton and shreddinginvertebrates (Melack & Fisher, 1990;Wantzen, Yule, Mathooko, & Pringle, 2008;Warfe et al., 2011). The interactions between rivers and their surrounding floodplain motivated Junk, Bayley, and Sparks (1989) to propose the 'flood pulse concept' as a main force controlling the biota of tropical floodplains. They considered the floodplain as the area periodically inundated by the waters of rivers, lakes, lagoons, and/or underground water, or by direct precipitation. The concept aims to explain the physical and chemical conditions that obligate the biota to respond through different phenological, morphological, anatomical and/or physiological adaptations to predictable hydrological cycles. Given its alternation between aquatic and terrestrial phases, the flooded area of the shoreline is defined as 'aquatic-terrestrial transitional zone' (AT...