Catalpa bignonioides aka Southern Catalpa

Catalpa bignonioides, or southern catalpa, is a deciduous shade tree. It belongs to the trumpetvine family, Bignoniaceae. Its native range spans the southeastern United States. Kew places it from east Texas to southern Georgia. It grows beside streams and rivers in rich, damp soil. Planted trees can spread beyond gardens through their winged seeds. The tree grows fast and can live for many years.

Garden trees often reach 30–40 feet (9.1–12.2 m) tall. Some reach 60 feet (18.3 m). Their spread ranges from 20–40 feet (6.1–12.2 m). A short, thick trunk supports a broad, uneven crown. Branches spread in crooked lines and can break easily. Dark gray bark has shallow cracks and reddish-brown scales. Young twigs start green, then turn reddish brown. Large, simple leaves grow opposite each other or in whorls. They have heart-shaped bases, smooth edges, and pointed tips. Fine hairs cover parts of the leaf undersides. Crushed leaves smell bad, and fall brings little color.

White, scented flowers form upright clusters near branch tips. Each bell-shaped bloom bears yellow and purple marks inside. Flowering runs from May to June in some gardens. Other sources place bloom later in summer. Bees visit the flowers, and two native sphinx moths use the tree. Long, thin seed capsules hang down from the branches. These pods reach about 1.25 feet (0.38 m) long. They turn dark brown in fall and split lengthwise. Seeds ripen from October to December. Pods may stay on the tree through winter and spring.

Grow this tree in full sun or partial shade. It does not grow well in full shade. It favors fertile, moist loam with good drainage. Yet it accepts clay, sand, and a broad pH range. It also tolerates dry soil, wet soil, and seasonal floods. Sources rate it for USDA zones 5–9 and UK H6. Shelter helps keep strong winds from tearing its large leaves. Young trees need protection from late spring frost. It serves as a lawn, street, or rain-garden tree. Its roots can help hold soil against erosion. People use its wood for fence posts, cabinets, and indoor finishes.

Serious pest problems are uncommon, but caterpillars can strip leaves. Aphids, scale, mealybugs, and whiteflies may also occur. Diseases include wilt, mildew, leaf spots, and twig blight. Honey fungus occurs rarely. Wind and hail can spoil the foliage. PFAF lists no known food uses and reports highly poisonous roots.