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 The beans pods on the catalpa are nearly as beautiful as the flowers. : r marijuanaenthusiasts 10 Benefits of Having a Northern Catalpa 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 Catalpa: Care and Growing Guide