Northern Catalpa Catalpa Speciosa Deciduous Trees Cold Stream Farm The Northern Catalpa Tree Extension Northern Catalpa Ohio Department of Natural Resources Smoke Catalpa Pods Catalpa (Catalpa speciosa) The Northern Catalpa Tree Extension 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 pods Biography of Durham's Finest Tree* No. 10: Parkwood Southern Catalpa ( Catalpa bignonioides) Extension Master Gardener Volunteers of Durham County