Is Northern catalpa Safe for Children? 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 Northern Catalpa (Catalpa speciosa) organically grown flower seeds. Floral Encounters. Northern Catalpa (Catalpa speciosa): A Complete Guide Smoke Catalpa Pods Catalpa (Catalpa speciosa) The Northern Catalpa Tree Extension