Have you seen the catalpa trees blooming? Most northern catalpas grow to heights of 60 feet, and in the late spring are filled with wonderful white blossoms. If you’ve ever looked at one of the blossoms up close it resembles an orchid. Flowering takes place in late spring to early summer.
The flowers occur in large clusters of showy, bell shaped corollas of five lobes with ruffled edges and yellow, orange or purple interior spotting or streaking. Individual flowers are tubular shaped and measure as much as 1/2-inch across. They usually appear in clusters at the leaf tips and the clusters measure as much as 10 inches across. The flowers are good for honey production.
The northern catalpa tree is generally described as a perennial tree. It is a native to the United States although it is in the same family as the trumpet vine, which is native to warm temperature regions of North America, the Caribbean and East Asia.
The largest living catalpa tree is on the grounds of the Michigan State Capitol in Lansing, Mich. It was planted in the year of its dedication, 1879. The oldest is the 150-year old specimen in the Minster graveyard of St. Mary’s Butts in the English town of Reading in Berkshire. The name derives from the Catawba Native American name Catawba (the tribal totem). The spelling “catalpa” is due to a transcription error on the part of the describing botanist making the first formal scientific description of the genus.
The rules of botanical naming state that the spelling used in the formal scientific description has to be retained for the scientific name. And so we call it a catalpa.
European settlers planted catalpa trees to produce fence posts. The wood is lightweight, and the heartwood is resistant to deterioration when placed in the ground for several years. Railroad companies grew plantations of catalpas for use as track ties and fuel wood. It was also used for making packing materials. Carpenters commonly used it for interior trim in houses. Craftsmen used it to make furniture.
Pioneer doctors used the seedpods and seeds to make a decoction for chronic bronchial affections, spasmodic asthma, breathing problems and heart problems. The juice from either the leaves or roots would be used to treat swelling of an eye, green leaves were crushed and placed on swollen lymph glands and the bark was dried and ground to powder and taken in the form of tea to treat swollen lymph glands. Modern pharmaceutical research has shown catalpa trees are diuretic.
It is sometimes planted to attract the green catalpa worms, which are prized fishing bait. The caterpillars can be frozen and used as bait at a later time.
The catalpa is a hardy deciduous tree that readily grows in USDA hardiness zones 4 to 8. It has moderate to fast growth, tending to grow rapidly when juvenile, but slowing with maturity. The height at 20 years is about 20 feet.
Catalpas prefer moist, deep, well-drained soil, but will adapt to dry or wet soils. The soil pH may range from 5.5 to 7.0. It prefers an open sunny place to partial shade. Catalpas grow tall, with an irregular, open-rounded to narrow-oval crown. The tree comes into leaf very late in the spring and is one of the first trees to lose its leaves in the fall.
The bark ranges from scaly to ridged, to blocky plates. On a mature tree trunk the bark may be from 3/4- to 1-inch thick, light grayish brown in color. On young tree seedlings the bark is thin and easily damaged by impact or rodents. Leaves are generally opposite on large branches and often whorled in three on young stems.
Leaves may scorch and drop during droughts. They turn an undistinguished yellow in the fall before dropping. Seedpods are slender and green in the summer growing from 10 to 24 inches long, looking similar to an exaggerated green bean. The seedpods mature in the fall, turn dark brown, split open lengthwise to let seeds fall in the spring.
The whole pod is often blown off the tree, and need to be picked up prior to mowing, as they are very hard and tough. The shape and color of the mature seedpods gives rise to the common name of cigar tree.
The northern catalpa is easily found in nurseries, garden stores and other plant dealers and distributors. It can be propagated by bare root, container or seed. It has a slow ability to spread through seed production and the seedlings have medium vigor.
When placed as an ornamental in a yard setting care must be taken to ensure it is not too close to a building, fence, property line or septic system. Ample space must be provided to let it reach a mature height.
Shirley Blizek is a Chippewa Valley Master Gardener Volunteer.