<i> Catalpa Chilopsis </i>

Chitalpa

A cross between Catalpa bignonioides and Chilopsis linearis

Deciduous, flowering tree, to 30 feet

Granted, the chitalpa is a striking tree, but the most interesting thing about it may be its background. A cross between two native American trees, the common catalpa and the desert willow, its roots are in the Soviet Union.

One of the main purposes of botanical gardens in the Soviet Union is to test and introduce new plants for potential use in the various climates of that country.

The climate of the Botanical Garden of the Uzbek Academy of Sciences in Taschkent is not unlike the Southwestern part of the United States: It is hot and dry, and the summers are without rain. From seeds probably obtained through a seed exchange list, Catalpa bignonioides , popular in the East, and Chilopsis linearis , from the Southwest, were crossed. The result, which is now called “chitalpa,” was first described in 1964 in a botanical journal in Moscow.

Seeds and cuttings of the chitalpa were obtained by the United States in 1977 through an international botanical exchange program under the direction of Dr. Thomas S. Elias, now director of the Rancho Santa Ana Botanic Garden in Claremont. The specimens were taken to the New York Botanical Garden, where they were grown and, in 1982, distributed to growers and other botanical gardens in the nation.

Chitalpa has “a lot of potential as a medium-size ornamental tree,” Elias says, with “the best qualities of both parents.” It is drought resistant and takes the cold to about minus 10 degrees Fahrenheit. In Southern California, it begins to bloom in March and can go strong all the way until September. The big, catalpa-like pale-pink flowers bloom in branched, upright clusters. The leaves of catalpas are broad and rounded, and those of desert willows are narrow. Chitalpa leaves are narrow and elliptical, giving the tree a light and airy appearance.

Rounded in overall form and growing to about 30 feet, it tends to be multi-trunked with low, spreading branches to 18 to 20 feet. (If left to its own, it cannot be walked under.) Most trees available in Southern California are trained to standard tree, or lollipop, form.

This is what is called an intergeneric hybrid--hybrids are usually crossed species, but the parents of chitalpa are from different genera (however, they are closely related--from the same family, Bignoniaceae). The offspring have yet to produce fruit or seed, but the plant roots easily from cuttings.

One drawback to the new tree is that it can get leaf mildew as crape myrtles do.

Chitalpa trees can be seen now, in bloom, at Rancho Santa Ana Botanic Garden, planted in the parking lot and in the Experimental Garden. At age 6 or 7, they are 12 to 14 feet tall, about half the size they’re going to be when mature.

Available from local nurseries, which can order 5-gallon containers directly from Monrovia Nursery Co. in Azusa.