RESUMO
We studied three cerrado physiognomies (campo cerrado, a savanna woodland; cerrado sensu stricto, a woodland; and cerradäo, a tall woodland) in a reserve with 1,225 ha, in Santa Rita do Passa-Quatro (21°36-38'S and 47°36-39'W), Säo Paulo State, South-eastern Brazil, to compare plant communities structure. As descriptors of the vegetation structure, we used richness, density, basal area, cylindrical volume, and diversity. Ten 40 m² quadrats were placed randomly in each physiognomy, in which we sampled the woody plants with stem diameter equal or larger than 1 cm (woody component), and ten 2.5 m² quadrats, in which we sampled the woody plants with stem diameter smaller than 1 cm and all the non-woody individuals (herbaceous component). In the woody component, we found significant differences among the physiognomies for richness, density and cylindrical volume. Cylindrical volume increased from campo cerrado to cerradäo, but richness and density were higher in cerrado sensu stricto. In the herbaceous component, we detected differences for all variables, which were higher in the savanna physiognomies, campo cerrado and cerrado sensu stricto, than in the forest physiognomy, cerradäo. Cylindrical volume was the best variable to distinguish the physiognomies. Floristic similarity followed the campo cerrado-cerrado sensu stricto-cerradäo gradient, and beta diversity was higher in the herbaceous component