Cauliflory is an unusual condition that evolved multiple times in the plant family Bignoniaceae and is found in three of the eight tribal-level clades that are recognized in the family (i.e. tribe Bignonieae, Paleotropical clade, and Tabebuia Alliance). We found a new cauliflorous species of Bignoniaceae during fieldwork in the Atlantic Forest of Brazil conducted as part of ongoing taxonomic and phylogenetic studies in Adenocalymma (tribe Bignonieae). This new species is here described as Adenocalymma cauliflorum. The new taxon resembles A. macrophyllum in the cauliflorous habit and A. cinereum in the yellow and tubular corolla, with anthers and stigma exserted. Here, we present a detailed description for Adenocalymma cauliflorum, an illustration, and information on its habitat, phenology, distribution and extinction risk. A key for the cauliflorous species of Adenocalymma is also presented.