Most Catalpa are deciduous trees; they typically grow to tall, with branches spreading to a diameter of about. They are fast growers and a 10-year-old sapling may stand about tall. They have characteristic large, heart-shaped leaves, which in some species are three-lobed. The appearance of the leaves sometimes causes confusion with species such as the unrelated tung tree and Paulownia tomentosa. Catalpa species bear broad panicles of showy flowers, generally in summer. The flower colour generally is white to yellow. In late summer or autumn the fruit appear; they are siliques about long, full of small flat seeds, each with two thin wings to aid in wind dispersal. The large leaves and dense foliage of Catalpa species provide good shelter from rain and wind, making the trees an attractive habitat for many species of birds. They do not present many threats of falling limbs, but the dark-brown fruit husks that they drop in late summer may be a nuisance. Though Catalpa wood is quite soft, it is popular for turning and for furniture when well seasoned, being attractive, stable and easy to work. Most catalpas begin flowering after roughly three years, and produce fruit after about five years, although Haitian catalpa can flower after six months growth from seed and produce seed after 18 months.
Species
The two North American species, Catalpa bignonioides and Catalpa speciosa, have been widely planted outside their natural ranges as ornamental trees for their showy flowers and attractive shape, or growing habit. Northern and southern catalpas are very similar in appearance, but the northern species has slightly larger leaves, flowers, and bean pods. Flowering starts after 275 growing degree days. Catalpa ovata from China, with pale yellow flowers, is also planted outside its natural range for ornamental purposes. This allowed C. bignonioides and C. ovata to hybridize, with the resultant Catalpa × erubescens also becoming a cultivated ornamental.
The name derives from the Muscogee name for the tree, "kutuhlpa" meaning "winged head" and is unrelated to the name of the Catawba people. The spellings "Catalpa" and "Catalpah" were used by Mark Catesby between 1729 and 1732, and Carl Linnaeus published the tree's name as Bignonia catalpa in 1753. Giovanni Antonio Scopoli established the genusCatalpa in 1777. The bean-like seed pod is the origin of the alternative vernacular namesIndian bean tree and cigar tree for Catalpa bignonioides and Catalpa speciosa, respectively.
Food source
The tree is the sole source of food for the catalpa sphinx moth, the leaves being eaten by the caterpillars. When caterpillars are numerous, infested trees may be completely defoliated. Defoliated catalpas produce new leaves readily, but with multiple generations occurring, new foliage may be consumed by subsequent broods. Severe defoliation over several consecutive years can cause death of trees. Because the caterpillars are an excellent live bait for fishing, some dedicated anglers plant catalpa mini-orchards for their own private source of "catawba-worms", particularly in the southern states.
Other uses
Catalpa is also occasionally used as a tonewood in guitars.
