Northern Catalpa Catalpa Speciosa Deciduous Trees Cold Stream Farm Smoke Catalpa Pods Catalpa (Catalpa speciosa) The Northern Catalpa Tree Extension 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 Learn About Northern Catalpa Arbor Day Foundation Northern Catalpa (Catalpa speciosa): A Complete Guide