While catalpa trees are not generally considered highly toxic, some parts of the tree, particularly the roots, are known to be poisonous according to the USDA Plants Database. The leaves and seed Catalpa bignonioides Indian Bean Tree, Southern catalpa PFAF Plant Database Catalpa Campus Trees Children exposed to marijuana smoke may absorb drug traces Polycyclic aromatic hydrocarbons and cannabinoids in secondhand cannabis smoke ScienceDirect Catalpa Campus Trees