Sonoma County Master Gardeners Helping Sonoma Gardeners

By Gwen Kilchherr, Sonoma County Master Gardener

The Chitalpa is as unlikely a tree as anyone might imagine. After all, who ever would have thought that the cross between Catalpa bignonioides (Southern catalpa), not the most desirable shade tree, and Chilopsis linearis, (Desert willow), not quite a stately specimen, would turn out so well? But it did! And here we have the Chitalpa! Scientifically, it is known as X Chitalpa tashkentensis.  That ‘x’ is not a typo – it indicates that the plant is a result of a cross between two different genuses.

 

Perhaps A. Russanov of the Botanic Garden of the Uzbek Academy of Sciences in Uzbekistan, way back in 1964, didn’t feel the same way about the parent trees when he created the hybrid between the Chilopsis and the Catalpa. Both belong to the Bignoniaceae, or trumpet vine, family.  The cross finally made its way to the US in 1997, when Robert Hebb of the New York Botanic Garden introduced it here. The hybrid remained unnamed until the Rancho Santa Ana Botanical Gardens in Claremont, CA, gave it the common name “Chitalpa.” The gardens also named two Chitalpa cultivars: ‘Morning Cloud’, with white flowers, and ‘Pink Dawn’, with pink.  Most Chitalpa trees produce large, orchid-like, white flowers, but ‘Pink Dawn’ features pink blooms with yellow throats.

 Chitalpa carries some of the best traits of both parents, yet doesn’t produce the abundant, messy seed pods that each parent tree develops.  That’s because the flowers are sterile. Therefore, there are no seed pods to drop onto patios and sidewalks, causing a slippery mess.  Anyone that has a desert willow knows how annoying this can be!

 Chitalpa has a lot going for it. For one thing, it appears to be more tolerant of poorly drained soils than desert willow, and it produces larger, orchid-like flowers. It starts flowering in May or June and extends until frost, unlike the once-in-the-spring-flowering Catalpa. Chitalpa flowers are borne in large clusters, each containing 15- to 40-inch-long florets that attract butterflies, bees and hummingbirds.

Chitalpa is a sun loving, fast-growing, multi or standard-trunked, deciduous tree needing occasional watering once established. The multi-trunked tree branches out near the base and creates an oval shaped canopy. The standard-trunked trees also have an oval shape to them. They both have an open limb structure, allowing filtered sun to pass through so other plants can grow underneath. Its desert willow-like, glossy green leaves are about 1 inch wide and can grow up to 4-6 inches long.

Reaching about 25 feet high and wide, Chitalpa’s appearance favors the desert willow, having the same open, breezy-like structure, but is much more lush-looking. This tree is considered drought-tolerant and is fairly hardy, surviving temperatures as low as 0 degrees F (USDA hardiness Zone 6). Its leaves and stems may suffer damage in cold weather, though it recovers in spring from the surviving roots.  It can be grown throughout Sonoma County successfully.

People are starting to take notice of Chitalpa’s terrific attributes. Several cities in Western states have begun recommending Chitalpa as a street tree, a drought-tolerant selection for urban settings and for use under utility lines.  It is also a smaller flowering tree that fits in well with many contemporary landscapes.

Again, who would have thought such a terrific tree would be the result of a cross between desert willow and catalpa? Chitalpa certainly inherited the best of both parents, making this tree an outstanding performer in just about any garden!

 ©Sonoma County Master Gardeners