Pronounciation: Chi-TAL-pa tash-ken-TEN-sis
Landscape Use: Oasis landscape design themes, multiple or single trunk residential tree, smaller park tree.
Form & Character: Partially to fully deciduous small tree, open, airy, festive when in bloom.
Growth Habit: Woody, winter deciduous, perennial tree, rather vigorous and rangy (correlative inhibition of lateral branching), upright and spreading to 30 feet in height with an equal or greater spread, marginally pendulous.
Foliage/texture: Variable alternate leave arrangement, sometimes whorled or ternate, leaves lanceolate and glabrous sometimes slightly reflexed, 2 to 5 inches long, rarely falcate, sometimes drops leaves prematurely in mid summer to early fall, stems and trunk has lenticels, no fall color; medium coarse texture.
Flowers & fruits: 15 to 40 flowers in a terminal raceme, corollas are zygomorphic, calyx are 2-lobed, color is white to pale or dark pink and often with distinct purple veins, flowers are sterile and produce no fruit.
Seasonal color: In Phoenix, flowers are grown during late spring and early summer.
Temperature: Tolerant of lower desert heat, though because of its relative sparse canopy it is VERY PRONE to trunk sunscald.
Light: Avoid western exposures with reflected radiation as this tree's trunk will sustain mega-sunscald damage!
Soil: Tolerant of high alkaline soils, though clearly less tolerant than Chilopsis linearis.
Watering: Chitalpa very much needs frequent, regular supplemental water, especially in summer. Its water needs for good performance in Phoenix are much higher than C. linearis because of its other "eastern" parent, the catalpa tree.
Pruning: Prudently and conservatively use selective thinning and heading of lateral branches to increase canopy density and aesthetics by reducing this tree's normal open, rangy branching habit.
Propagation: Asexually only by stem cuttings.
Disease and pests: This hybrid tree is highly subject to Thielaviopsis root rot and more critically, Xylella fastidosa (Pearce's disease), a leaf scorch bacteria that normally infects grapes. Otherwise, foliar powdery mildew is usually confined to wet spring conditions, which in central Arizona are increasingly becoming rare because of climate change in the desert Southwest.
Additional comments: Chiltalpa is an unusual intergeneric hybrid cross created in Uzbekistan in 1964 and introduced to the United States by Robert Hebb of the New York Botanic Garden in 1977. This fruitless botanical freak has been commonly seen in Phoenix landscapes since only 1990. Named cultivars include 'Morning Cloud' (white flowers) and 'Pink Dawn' (deep pink flowers). Chitalpa has a relatively sparse canopy, is prone to trunk sunscald, and requires frequent and regular summer water in Phoenix. It is best used away from reflected radiation or intense western exposures.