The native ranges of the two types of catalpa trees that grow in the United States are somewhat uncertain, since the tree has long been a popular ornamental and people planted it across much of the East. The catalpas belong to the Bignonia family, a group of mostly tropical plants; the northern catalpa is the most northerly ranging of this group. The catalpas have interesting features, such as very large leaves and hanging seedpods.
The northern catalpa can grow to 100 feet high and averages between 60 and 80 feet. The southern catalpa is a smaller species, with an average individual about 50 feet tall. The trunk diameters of the catalpas are in the 2 to 3 foot range. Catalpas grow rather quickly but are short-lived. The Georgia School of Forest Resources Extension site says a southern catalpa typically lives for only 70 years.
The leaf shape of the catalpa’s foliage bears a great likeness to elephant ears or large hearts. Their size makes them a prominent feature, as those on a northern catalpa can be a foot in length and as wide as 8 inches; the southern catalpa leaves are slightly smaller. The leaves grow three at each node on the twig in a whorled pattern and are a dull shade of green above with a hairy pale underside. The leaves turn blackish before falling off the tree in autumn.
The nicknames of the cigarette tree, bean tree and Indian bean tree come from the catalpa’s seedpods, which develop from a showy bell-shaped bloom with splotches of yellow and purple on a mostly white flower. The flowers are perfect, meaning they contain male and female parts, so all catalpas will develop the fruit (seedpods). The pods are as long as 18 to 20 inches on the northern variety and a couple inches shorter on the southern type. The pods are green to start off, but eventually change to a dull brown on both species, persisting on the trees through winter until opening the next spring and releasing the seeds.
The catalpas are easy to transplant and grow in many types of soils—and needs a full sunshine locale or a partial sun location. Catalpas make excellent shade trees and landscaping species, with the leaves, flowers and finally the pods giving the tree appeal. However, the tree is a messy one for homeowners, requiring much maintenance beneath it, as the various features gradually fall to the ground and accumulate.
The original range of the southern catalpa is now four times what it once was, with the tree's use as an ornamental being the reason. The heartwood of the catalpa is resistant to the effects of rot and makes excellent fence posts. Catalpa trees fall victim to high winds and ice storms, losing branches during these weather events. The larvae of the Catalpa sphinx moth can chew the leaves and damage a northern catalpa. The catalpa is the sole plant that these caterpillars attack.