Catalpa x erubescens ‘Purpurea’

I’ve always enjoyed catalpas (Catalpa sp.) in the landscape. In Janesville, Wisconsin, where I live, there are some old, venerable specimens in yards and parkways. Their bold foliage, beautiful flowers, cigar-shaped seed pods and broad adaptability in the landscape are all appealing. I also have become a fan of the harder-to-find purple catalpa (Catalpa x erubescens ‘Purpurea’). This unique catalpa is an excellent specimen tree with many attributes of interest.

This purple selection is thought to originate from France in the late 19th century. This fast-growing, hybrid catalpa is a cross between the native southern catalpa (Catalpa bignonioides) and the Chinese catalpa (Catalpa ovata). With a lush, tropical appearance, the new growth of large, broad, heart-shaped leaves flushes out a very deep purple with older leaves fading to a bronze green and ultimately green. While the purple intensity is the most dramatic in spring, evidence of the darker foliage persists throughout the season until some shades of golden yellow fall color appear.

The flowers of this hybrid are consistent with other catalpas in appearing in late spring to early summer on panicles showcasing white, “foxglove-like” blooms featuring maroon speckles and orange-yellow accents. Flowering even at a young age, the exquisite blooms quite fragrant and also attract bees, butterflies and hummingbirds. Later, long (14 to 20 inch) and narrow pods (capsules) are formed and dangle from the tree into the winter months. These bean-like pods support the historic common names of “cigar tree” and “Indian bean tree.”

Hardy in USDA Zones 5-9, purple catalpa is thought to achieve a height and width of 40 feet or more. This tree is fine in full sun or part shade. Admittedly, I’ve not seen specimens over 25 feet tall in the Midwest, but imagine they will continue to gain size. Specimens can be kept shorter with coppicing or even cut low to the ground for a shrub-like habit. Moist, fertile and well-drained soils are ideal although catalpas are also remarkably urban tolerant (including heavy salt tolerance). Purple catalpa also has very few insect and disease problems and is notably resistant to honey fungus (Armillaria). This selection is best propagated by softwood or semi-hardwood cuttings.

The bold, textural contribution of this tree, combined with the deep purple new growth, makes purple catalpa an ideal specimen tree and conversation piece in the landscape. The flowers are spectacular and the options for successful use of this uncommon tree seem limitless.