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 Northern Catalpa (Catalpa speciosa) MyGardenLife Northern Catalpa Catalpa Speciosa Deciduous Trees Cold Stream Farm Catalpa bignonioides Indian Bean Tree, Southern catalpa PFAF Plant Database Biography of Durham's Finest Tree* No. 10: Parkwood Southern Catalpa ( Catalpa bignonioides) Extension Master Gardener Volunteers of Durham County How to Choose, Plant, and Grow a Catalpa Tree HGTV