Southern Catalpa

Arbor Walk #115

The Southern Catalpa is a smaller relative of the Northern Catalpa, keeping the large cordate leaves and long seed capsules, but with more vivid flowers and unpleasant-smelling leaves. Although it is relatively constrained in its native range in the Southeastern U.S., it is able to withstand a variety of conditions and has naturalized in many places across North America. Ecologically, the Southern Catalpa supports the Catalpa Sphinx moth, which can prodigiously defoliate the tree while causing no long-term damage.

Common Name(s)Southern Catalpa
Latin NameCatalpa bignonioides
Indigenous Name(s)
Cultivar/Variety
Commercial Name
Global Distribution
Where to find Arbor Walk #115 on WashU campus
Our Southern Catalpa in space
GPS Coordinates

N/A

Percent Concrete

N/A

Distance to Buildings
YearClose Building #1Close Building #2Close Building #3
Distance to Other Species
YearClose Species #1Close Species # 2Close Species # 3
Our Southern Catalpa through time
Standard Measurements
YearHeight (m)DBH (cm)Crown Diameter N-S (m)Crown Diameter E-W (m)Average Crown Diameter (m)
20234.441.111.521.315
Nests and Pests
YearDescription
2023N/A
How to identify a Southern Catalpa
Leaf Identification

The leaves of the Southern Catalpa is typically 10″ to 12″ long and 5″ to 7″ wide. The leaf shape is usually cordate (heart-shaped) but can appear ovate as well. The margin is entire, and the venation is pinnate. The leaf arrangement can be opposite or whorled. The leaves have an unpleasant odor when damaged.

Twig and Bud Identification

The twig of the Southern Catalpa can be green to reddish-brown. It lacks a terminal bud, but the lateral buds are small and covered with reddish-brown scales.

Bark Identification

The Southern Catalpa’s bark contain irregularly shallow fissures. With age, it gains reddish-brown scales.

Fruit Identification

The fruits of the Southern Catalpa are long and thin pod-like capsules. They are 8″ to 15″ long, and turn brown when mature. The seeds release when the pod splits open in the fall or winter.

Flower Identification

The flowers of the Southern Catalpa form panicles. They are white with yellow stripes and speckled purple streaks. The flowers are bell-shaped with ruffled fringes along the petal margin. They bloom in spring.

Catalpa ID Tips
  • The Southern Catalpa is smaller than the Northern Catalpa, and its capsules are slightly smaller as well, not reaching above 15″.
  • The flowers of the Southern Catalpa are more vivid in color and clustered tighter than those of the Northern Catalpa.
  • Perhaps most easily discerned, the Southern Catalpa has leaves which give off a bad odor when crushed, while the Northern Catalpa does not.
Relationship of Catalpa bignonioides to other species in the arboretum
Additional resources on the Southern Catalpa