[7] Catalpa bignonioides is a deciduous tree growing to 25–40 feet (7.6–12.2 m) tall with an equal or greater spread,[8] with a trunk up to 1 metre (3 ft 3 in) diameter, with brown to gray bark, maturing into hard plates or ridges.

The short thick trunk supports long and straggling branches which form a broad and irregular head.

They appear late, and as they are full-grown before the flower clusters open, they add much to the beauty of the blossoming tree.

They secrete nectar, a most unusual characteristic for leaves, by means of groups of tiny glands in the axils of the primary veins.

Page 319 The flowers are 2.5–4 cm across, trumpet shaped, white with yellow spots inside; they grow in panicles of 20–40.

The nectar in turn attracted a greater number of bodyguard ants Forelius pruinosus to the damaged leaves, thus giving added protection to the whole plant.

[9] Despite its southern origins, it has been able to grow almost anywhere in the United States and southernmost Canada, and has become widely naturalized outside its restricted native range.

[citation needed] The catalpa has the distinction of bearing some of the showiest flowers of all the American native trees.

Its value in this respect has long been recognized and it holds an assured place in the parks and gardens of all temperate countries.

[9] The wood is brittle and hard, but does not rot easily;[citation needed] it is used for fence posts and railroad ties.