Abstract. This paper analyses the floristic variation in the southern segment of the Oriental Chaco, known as the Santa Fe Forest Wedge. Floristical variation in Chaco forests is described at three levels of scale. On the coarsest scale there is a gradient of increasing floristic richness towards the north, related to a geographic temperature gradient. At an intermediate scale different types of forests are arranged according to environmental gradients correlated with topographic elevation. At a fine scale many microsites can be discerned with different micro‐environments colonized differentially by species. Microsites arise as the result of site‐physiographic history, development of vegetation and the interaction of both and with animals. Several dimensions of regenerationniche variation are distinguished, including canopy and soil characteristics, and propagule dispersal.