In 1988 Gordon Guymer of the Queensland Herbarium published a taxonomic revision of "Brachychiton"; he classified "B. rupestris" in the section "Delabechea" along with the related and newly described Proserpine bottle tree. A third species, from southeast Queensland, has been recognised but not yet described. Unique to the section, all three species have bulbous trunks and can have large cavities in the vertical wood parenchyma. The genus "Brachychiton" lies within an Australasian clade within the subfamily Sterculioideae (previously family Sterculiaceae) in a large broadly defined Malvaceae. It is only distantly related to "Sterculia", belonging to a different clade within the Sterculioideae.