Catalpas are deciduous trees with scaly buds. Terminal buds are absent. Leaves are opposite or whorled and carried on long petioles. Leaf margins are entire. Flowers are borne in terminal panicles and are quite showy. Fruits are long, narrow, pod-like capsules, separating into winged seeds in the spring.
| I. | Leaves are 6—12 inches (15—301/2 cm) long with acuminate leaf tips. Foliage has no odor when crushed. Flowers are white with yellow-striped or brown-dotted throats. Flowers are borne in comparatively small terminal panicles. Flowers open in June. |
| Catalpa speciosa–Northern Catalpa | |
| II. | Leaves are 4—8 inches (10—20 cm) long with abruptly acuminate leaf tips. Foliage has an unpleasant odor when crushed. Flowers are white with yellow stripes and brown dots in the throat. Flowers are borne in many-flowered clusters and open in June and July. |
| Catalpa bignonioides–Southern Catalpa |
Southern Catalpa–Catalpa bignoniodes
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| Southern Catalpa |
A small tree, not more than 20—40 feet high, the southern catalpa has widespreading branches that form an open head. The smaller size of the southern catalpa makes it desirable for small properties, but the litter is a concern in those situations. Often the southern catalpa was confused with the northern or hardy catalpa for reforestation purposes. Today neither catalpa is grown as a timber species.
Leaves are smaller than Catalpa speciosa and are only 4—8 inches (10—20 cm) long with abruptly acuminate leaf tips. Leaf attachment is opposite or whorled. Leaf bases are heart-shaped with entire leaf margins. Foliage is light green and smooth above and hairy, or nearly so, beneath, especially along veins. Leaves have an unpleasant odor when crushed.
Terminal buds are absent. Catalpas have small, hemispherical buds. Leaf scars are circular and look like small volcanos. Twigs are stout, heavily lenticeled, and downy. The color is red to yellowish-brown. Pith is white and continuous.
Flowers are borne in many-flowered terminal panicles and are quite showy. Flowers are white with yellow stripes and brown dots in the throat and open in June and July. Flowers open about two weeks later than the northern catalpa. Fruits are 6—20 inches (15—51 cm) long with narrow, pod-like capsules separating into winged seed in the spring. Fruit is conspicuous through the winter and a positive identification feature for catalpa in Ohio. Fruit and flowers are a litter problem.
Northern Catalpa–Catalpa speciosa
The hardy catalpa was originally native from southwestern Indiana to southeastern Missouri and northeastern Arkansas. The hardy catalpa has been widely planted in Ohio for ornamental purposes. They are thrifty trees that develop straight trunks and reach 75 feet in the forest. These trees are very urban-tolerant. Litter from foliage, flowers, and fruit is a concern in landscape settings and falls throughout the year.
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| Northern Catalpa |
The simple leaves are opposite or whorled and carried on long petioles. Leaves are 6—12 inches (15—301/2 cm) long and 4—5 inches (10—13 cm) wide. Leaves are heart-shaped at the base with acuminate leaf tips. Leaf margins are entire. The bruised leaves have no odor.
Catalpas have imbricate or scaly buds. Terminal buds are absent. The twigs are stout, smooth, yellowish-brown, and marked with large leaf scars. Leaf scars are circular and look like small volcanos. The buds are very small. Twigs are stout, heavily lenticeled, and downy. The color is red to yellowish-brown. Pith is white and continuous. The bark on old trees is fissured, ridged, and dark gray-brown.
Flowers are borne in erect, 8—10 inch (20—25 cm) high terminal panicles and are quite showy. Flowers are white with yellow-striped or brown-dotted throats and open in June. The lower lobe of the corolla is notched. Fruits are 12 inches (301/2 cm) long with narrow, pod-like capsules separating into winged seeds in the spring. The fruit is conspicuous all winter and is a positive identification feature for catalpa in Ohio.
This species was formerly planted because of its rapid growth and durable wood. The wood is durable and light brown with a satiny surface and a kerosene-like odor. It is especially well-suited for fence posts and rails, as it lasts a long time in contact with the soil and does not require a preservative treatment. Insect damage has checked the growth of many plantations for use as fence posts.