Northern Catalpa (Catalpa speciosa) organically grown flower seeds. Floral Encounters. Learn About Northern Catalpa Arbor Day Foundation Smoke Catalpa Pods Catalpa (Catalpa speciosa) The Northern Catalpa Tree Extension Tree Tales: Call of the Catalpa Go Green Brooklyn 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