Chitalpa vs. Desert Willow vs. Catalpa

Desert Willow or Desert Catalpa

While writing on the Desert Willow, I thought I'd share something that confuses a lot of Tucson gardeners.....the differences between the Chitalpa and the Desert Willow.  What do they both mean?  And how do you tell them apart?  Both trees grow here and both have similiar growing habits.  Generally, they are similiar plants with the exception that the Desert Willow is a native for Southern Arizona as it grows along canyon beds and rivers here.  The Chitalpa is a bit more tropical in appearance with thicker leaves. Catalpa is yet another tree that I occassionally see around Tucson, but I wouldn't recommend growing this one as it can receive severe damage from our cold nights. People have reported, through my various questions, that their trees suffered cracking in their trunks during extreme frosty nights. This is definitely a more tropical type tree.  I think I'd put this one in a pot if you want to try it out. So what are the differences? And why are they important?

Chitalpa

If you look at the pic of the chitalpa, you'll notice thicker leaves and a slight color varietation. The chitalpa also has different colored flowers when compared with the traditional bright pink of the Desert Willow.  Why are these two trees similiar?
The Chitalpa, X Chitalpa tashkentensis, is a hybrid between the Desert Willow and Catalpa tree.  This combination is a hit for many people and were designed for our desert community.  Here is some info from Dr. David L. Morgan on the Chitalpa tree....

"The chitalpa is as unlikely a tree as one might imagine. After all, who would’ve thought the cross between the catalpa (not the most desirable shade tree) and the desert willow (one could hardly describe it as a stately specimen) would turn out so well? But it certainly did.

Perhaps A. Russanov of the Botanic Garden of the Uzbek Academy of Sciences in Uzbekistan didn’t feel the same way about the parent trees when he created the hybrid between Chilopsis linearis (desert willow) and Catalpa bignonioides (Southern catalpa) – both members of the Bignoniaceae, or trumpet vine family. That was back in 1964, when relations were icy between the US and the Soviet Union. The cross finally made its way to the US in 1997, when Robert Hebb of the New York Botanic Garden introduced it. 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 pale purplish-pink flowers and pale yellow throats).


Chitalpa carries some of the best traits of both parents, yet it’s sterile, so it doesn’t produce the abundant, messy seedpods of either. What’s more, its mature flowers don’t drop on sidewalks, causing a slippery goo, as does the desert willow on occasion.
Though not as widely grown as desert willow, chitalpa (scientifically known as X Chitalpa tashkentensis) 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. Its floral display begins 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 fast-growing, multi-trunked deciduous tree that branches near the base and creates an oval canopy. It has an open limb structure, allowing filtered sun to pass through and grass to grow beneath. Its desert willow-like, glossy green leaves are about 1 inch wide and can grow up to 6 inches long."


Source:  http://www.learn2grow.com/gardeningguides/trees/featuredplants/ChitalpaTrees.aspx