Southern Catalpa Catalpa bignonioides

The southern catalpa is a medium-sized, deciduous tree with a short, thick trunk and a broadly rounded irregular crown. It is native to the Gulf States, from Florida to Texas, and Georgia. This species is found in North Carolina, either escaping from or persisting after cultivation. It is a member of the trumpetvine family (Bignoniaceae). The name Catalpa is derived from the Muscogee name for the tree, "kutuhlpa," and the species epithet, bignonioides, means “like Bignonia,” which is a related genus.  

The southern catalpa is a relatively easy, fast-growing shade tree that prefers moderate soils but is tolerant of clay and wet or dry conditions, including seasonal flooding. In nature, it is most often found in rich moist soils by the sides of streams and rivers. It prefers being grown in full sun to part shade and will not grow in full shade. 

This long-lived tree has an irregular shape as it matures and blooms with white flowers that are about an inch and a half in width in early summer. Seed pods droop from the branches in a unique, string-like display. This tree has an extensive root system and is sometimes grown to stabilize soil. The tree’s irregular shape may not fit with the landscape; the seemingly randomly spreading and crooked branches can be off-putting, or they can be charming. In addition, while the flowers have a pleasant fragrance, the foliage is unpleasantly fragrant when crushed. Note that this tree also flowers later than C. speciosa, and the flowers have more of a purple color. The southern catalpa is a natural host to two native moths, the catalpa sphinx (Ceratomia catalpae) and the tersa sphinx (Xylophanes tersa), which are important food sources for birds and bats. 

The two US species can be distinguished as follows:

• C. bignonioides: Foliage with a fetid odor; lower corolla lobe entire; densely spotted with purple; seed wings rounded like a pointed paintbrush. 
• C. speciosa: Foliage with “green” odor; lower corolla lobe cleft; sparsely spotted with purple; seed wings flattened.

This species can be grown in a variety of landscape themes, including children’s gardens, rain gardens, and butterfly gardens. The winged seeds of this species give it a propensity for escaping cultivation. 

Insects, Diseases, and Other Plant Problems: No serious problems. Catalpa sphinx moth caterpillars can do significant damage but are rarely lethal. Mildew, twig blight, verticillium wilt, and leaf spots are occasional problems. Leaves can become damaged and look unsightly from wind or hail.