Tree of the Week: The northern catalpa

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The northern catalpa -- Catalpa speciosa

Spectacular in bloom with big, upright clusters of white flowers set off against big, bold leaves, the catalpa shouts for attention in spring. At other times, the impression is more of a country dweller lost in the city: Such as when the long-lasting Indian beans -- up to 20-inch-long, bean-like seed capsules -- dangle from the branches or when the sloppy twigs’ arbitrary direction of growth all over becomes exposed during the leafless seasons. Some find the tree messy and weedy looking, especially in winter.

Originally from Mississippi River valleys, an area stretching from Indiana to Northern Arkansas, this tough tree with the Indian name was widely planted for quick shade, durable fence posts and fine-grained wood. Occasionally it was used for avenue planting in Ohio. The tree is also known as western catalpa and is a member of the Bignonia family.

Fast growing when young, the deciduous northern catalpa eventually reaches 40 to 60 feet tall and 20 to 40 feet wide. It tolerates climate extremes. The crown will be irregularly shaped and the trunk and branches crooked, unless pruned. Wood is brittle. Shallow fissures and scaly ridges define the gray to reddish-brown bark, while round or elliptical leaf scars decorate the twigs. The soft, bright green, 6- to-12-inch-long heart-shaped leaves are fuzzy underneath and so tender and large that the wind may tear them apart; it is best to plant the catalpa in a protected spot.

White, bell-shaped flowers, 1 inch long, with yellow and purple spots on the insides, are arranged in footlong clusters. Long, thin, brown beans will follow and may stay on the tree for months. The catalpa is not particular as to soil and water. It is invasive in some areas of high moisture.

The closely related common or southern catalpa, C. bignonioides, is a bit smaller and the leaves release an odd odor when crushed. A hybrid with a Chinese species has blackish purple leaves. The otherwise similar-looking Empress tree, Pauwlonia tomentosa, with which the northern catalpa is sometimes confused, has lavender flowers.

-- Pieter Severynen

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