General: It is a perennial deciduous tree which readily grows in USDA Hardiness Zones 4 to 8. It has moderate to fast growth, tending to grow rapidly when juvenile, but slows with maturity.
The height at 20 years is about 20 feet. The biggest northern catalpa recorded is in Indiana. It is 85 feet tall with a spread of 81 feet and a circumference of 290 inches at 4.5 feet above ground level. Catalpas prefer moist, deep, well drained soil, but adapts to dry or wet soils. The soil pH may range from 5.5 to 7.0. It prefers an open sunny space to partial shade. When it grows from seed the tree trunk rarely divides into two or more branches about the same size. If the tree is cut and grows back there is prolific spouting from the stump. The bole may be straight, but it is usually crooked. It is tall with an irregular, open-rounded to narrow-oval crown. This tree comes into leaf very late in the spring and it is one of the first to lose its leaves in the fall. Its longevity is about 60 years.
The tree bark ranges from scaly to ridged, to blocky plates. On a mature tree trunk the bark may be from ¾ to 1 inch thick, light grayish brown in color, and broken into longitudinal, scaly, flat ridges. On young tree seedlings the bark is thin and easily damaged by impact, or rodents.
Twigs in winter have a unique identifying characteristic. They have sunken leaf scars which resemble suction cups. Their whorled arrangement of 3 scars per node is another trait easily identified.
Leaves are simple, large, ovate to ovate-oblong, from 8 to 12 inches long, are heart-shaped tropical looking without any lobes and are yellowish green in color. The leaf margins are entire, pointed at the tips and rounded to cordate at the bases. The top of the leaf is darker green than the underside which is also pubescent. Leaves are generally opposite on large branches and often whorled in 3 on young stems. Leaves may scorch and drop during droughts. They turn an undistinguished yellow in the fall before dropping. The leaves do not emit an unpleasant aroma when bruised as is the case with the southern catalpa (Catalpa bignonioides Walt.), which are also more abruptly pointed.
The flowers of catalpa are perfect. Flowering takes place in late spring to early summer. They occur as large clusters of showy, white, bell-shaped corollas of 5 lobes with ruffled edges and yellow, orange or purple interior spotting or streaking. Individual flowers are showy, tubular up to ½ inch broad. They are branched in about 10 inch clusters at the stem tips. The northern catalpa flowers about 2 to 3 weeks earlier than the southern catalpa, which also has more spotted flowers. Flowers are good for honey production.
Seedpods are slender and green in the summer growing from 10 to 24 inches long, looking similar to an exaggerated green bean. They 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. The shape and color of the mature seedpod gives rise to the common name of cigar tree.
The southern catalpa seeds are drawn out more to a point while the northern catalpas seeds are blunter at the end. Seeds are about 1 inch long and 1/3 inch wide. They have a light brown coat and wings rounded at the ends terminating in a fringe of short hairs. There are approximately 20,480 seeds per pound. Seeds which are collected after overwintering in the mature seedpod have a higher germination rate than those collected in the fall and stored.
The wood is of moderately light density (specific gravity 0.42 oven dry), with pale gray sapwood and grayish brown heartwood. It has a faint, aromatic, non characteristic odor and no characteristic taste. It is ring porous, coarse-grained, soft, not strong, but very durable in contact with the soil.
Distribution: For current distribution, please consult the Plant Profile page for this species on the PLANTS Web site.
Habitat: Prior to European settlement it was native to a small area of the central Mississippi Valley basin, western Tennessee, north east Arkansas, the lowlands of south east Mississippi and southern Illinois and Indiana. Farmers once planted catalpas in groves to provide shade for hog lots. It is now readily found from Kansas south to Texas and eastward to Louisiana.
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