Architectural models reflect the genetic designs of tree growth and development from their juvenile to adult phases and the balance between endogenous growth processes and exogenous environmental restrictions. We analyzed six species growing in xeric Caatinga vegetation in northeastern Brazil (Jatropha mollissima var. mollissima, Mimosa paraibana, Sarcomphalus joazeiro, Aspidosperma pyrifolium, Croton blanchetianus, and Pityrocarpa moniliformis) in terms of their architectural models and axis categories (growth modes, types of branching, branch geometry, and the presence or absence of reproductive structures). All of the species studied exhibited orthotropic orientation axes and rhythmic growth. As for the other axis categories, there were differences. Two architectural models were identified for the species: the Leeuwenberg model for J. mollissima and A. pyrifolium, and Rauh's model for C. blanchetianus, M. paraibana, S. joazeiro, and P. moniliformis. We identify the architectural models associated with the species analyzed, demonstrate their axis patterns, and provide a basis for future studies involving canopy architecture, especially with regard to the Brazilian semiarid region.