Underfoot: THE CIGAR TREE Northcentral Pennsylvania Conservancy Northern Catalpa (Catalpa speciosa) 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 Deciduous Trees Cold Stream Farm Northern Catalpa Catalpa Speciosa Deciduous Trees Cold Stream Farm