Catalpa speciosa aka Northern Catalpa

Catalpa speciosa, or northern catalpa, belongs to the trumpetvine family. This deciduous tree comes from the central and eastern United States. Kew gives its native range as extending west to Utah. It grows a thick trunk and a broad, uneven crown. Branches spread outward and may bend or twist. Garden trees often reach 40–60 feet (12–18.3 metres). Their spread is about 20–40 feet (6–12.2 metres). Some sources report heights of 70–80 feet (21.3–24.4 metres).

The grey to brown bark forms ridges and shallow cracks. Stout shoots start green, then turn reddish brown. Pale lenticels and large, round leaf scars mark the stems. The large, heart-shaped leaves have pointed tips and smooth edges. Leaves grow in opposite pairs or whorls near shoot tips. Soft hairs cover their lower sides. They turn yellow-green in autumn, without a strong colour display.

White, bell-shaped flowers grow in upright panicles at branch tips. Yellow or orange marks and purple spots line their throats. Bloom falls in May and June in Chicago. The RHS reports July flowering in Britain. Bees visit the flowers. Long capsules follow, reaching about 1.8 feet (0.56 metres). These start green and turn brown as they ripen. Some remain on the tree through winter. They split open and release winged seeds into the wind.

Grow this tree in sun or partial shade. It prefers deep, fertile, moist soil with good drainage. It also tolerates clay, poor soil, and wet or dry sites. The RHS lists acid, neutral, and alkaline soils as suitable. Chicago gives USDA zones 4–8; the RHS rates it H6. Shelter helps prevent strong winds from tearing the large leaves. Young trees need protection from late spring frost. Sources describe its growth as moderate to fast.

Northern catalpa serves as a lawn, street, park, or shade tree. It hosts catalpa sphinx and tersa sphinx moth larvae. Its light wood lasts well in soil and suits fence posts. Brittle branches, damaged leaves, and fallen pods can limit its appeal. Serious pest trouble is uncommon, but caterpillars may strip leaves. Leaf spots, mildew, twig blight, and verticillium wilt can occur. Honey fungus is a less frequent risk. UConn reports escape and spread in Connecticut. PFAF lists no known food uses or hazards. NC State also flags possible contact dermatitis.