The northern catalpa is a deciduous tree grown for its flower clusters and broad ornamental leaves. Originally native to the eastern region of the United States Midwest, the northern catalpa is hardy in most states of the country. The tree is known for the somewhat expansive growth pattern of its branches and can become quite large. It is also noted for its ability to tolerate a variety of soils and even poor growing conditions. The tree is additionally known as the western catalpa and by its scientific name, Catalpa speciosa.
Gardeners find the northern catalpa attractive for its large 2-inch (5-cm) white flowers. These grow in long clusters called panicles, which may reach 6 inches (15 cm) in length. Although at times the clusters may be sparse, they can also cover the entire tree. Individual flowers have yellow or purple shading at the center. Northern catalpas are notable in bloom because the many white flower clusters can be seen from some distance and give the tree a distinctive appearance.
Catalpas have wide, glossy leaves that can be as long wide as 12 inches (30 cm) across. The leaves may be tapered or more broadly heart shaped and have hairy undersides. Catalpa leaves grow either in pairs or in groups of three, which also gives the foliage a unique appearance. Together with their widely spaced branches, the large leaves may give catalpas a shaggy appearance at times.
Trees usually reach the height of their blooming period in early to middle summer. In autumn, the tree develops the long seed pods that give it the nickname Indian bean or Indian cigar tree. The seeds pods can be as long as 20 inches (50 cm). The northern catalpa develops very little color as leaves change in the fall. Instead, leaves are likely to brown and drop quickly after freezing temperatures have been reached.
The northern catalpa can be planted in most types of soil and requires little preparation of the site. It tolerates alkaline and acidic soils as well as periodic or uneven rainfall. Like all plants and trees, though, it will benefit from attention.
The catalpa can grow quite tall and reach ages of older than a century. They can reach heights of about 40 feet (12.2 m) and possibly much higher. Originally native to the region now composed of Illinois through Ohio, the northern catalpa has spread across the country due to cultivation. It is hardy in all but the very coldest and hottest regions of the U.S.