Cercidium thornless hybrid 'AZT' (Parkinsonia thornless hybrid 'AZT') 'AZT' Thornless Palo Verde
Foliage: Semi-Deciduous
Mature Height: 20’ - 30’
Mature Width: 20’ - 40’
Growth Rate: Fast
Hardiness: 18 degrees F
Exposure: Full Sun
Leaf Color: Green
Shade: Filtered
Flower Color: Yellow
Flower Shape: Funnel Shaped Petals
Flower Season: Spring
Thorns: None
Propagation Method: Cloning
Sizes Available: #25, #45, & 48"
Nothing heralds the arrival of the desert spring (and in some year’s 100 degree temperatures) as brilliantly and conspicuously as the blooming of the Palo Verdes. With a succession that includes Blue (Cercidium floridum), Foothill, Mexican and Sonoran, Palo Verdes color the desert a brilliant yellow from spring to early summer. Other than Mexican Palo Verde (Parkinsonia aculeata) all the Palo Verdes are popular and widely used landscape trees. All these species are so closely related botanically that hybridization between species is quite common in native and nursery environments. In the past this hybridization went largely unnoticed or was mistaken for genetic seed variation within a single species. The potential for Cercidium hybrids to offer genetic advantages like increased vigor, greater cold hardiness, enhanced flowering and the absence of thorns brought them to the attention of horticultural professionals and propagators.
Cercidium (Parkinsonia) hybrid ‘AZT™’ exhibits the form, structure and grace found in Palo Brea, Blue and Mexican Palo Verde in combination with a leaf canopy that provides ample shade with lush, green leaves. These trees are thornless and produce brilliant yellow flowers abundantly in spring, intermittently during the summer months and occasionally in the fall. Similar to the Palo Brea, the branches and trunks of variety 'AZT™' remain a smooth, lime green as they mature and possess the genetic versatility to be grown as either V-shaped upright or candelabra form specimens. The orientation and angles of branches are also a bit reminiscent of Palo Brea making the trees excellent “focal point” single specimens, theme trees, street and perimeter planting and can be dramatically up-lit at night. Cercidium hybrid ‘AZT™’ has 4 to 6 pairs of leaves with 15 to 24 pairs of leaflets per leave. These highly divided leaves produce a canopy that is lush yet airy and provides welcome filtered shade that promotes flowering of under-story shrubs and groundcovers. This hybrid is thornless, and a semi-evergreen growth.
Variety 'AZT':
More than a decade ago Arid Zone Trees (AZT™) began vegetatively propagating (cloning) some of our most popular desert adapted tree species. This process involved: 1) identifying trees that had both desirable physical qualities (branching habits, leaf color, leaf canopy, and flower color) and sound horticultural characteristics (rooting, cold hardiness and growth rate); 2) developing propagation techniques that allowed the large scale vegetative propagation of the selected trees; and 3) growing these selections to market sizes for additional nursery evaluation and field testing in landscape setting. This tree is the product of our research and evaluation. We have identified each of our clone species with the variety designation ‘AZT™’. Our rigorous screening and propagation process, in combination with AZT™’s Root Management Program, insures that Cercidium hybrid ‘AZT™’ brings beauty, durability and sound genetics to desert landscapes.
Cercidium hybrid ‘AZT™’ we are so confident of the quality, we put our name on it.
Cercidium (Parkinsonia) hybrid 'AZT™' is propagated and available exclusively from Arid Zone Trees.
Cultural Practices:
Foster the development of a more dispersed root system and reduce the risk of wind throw by arranging irrigation emitters at varying distances from the trunk to encourage roots to "seek out" water and nutrients. Irrigation emitter arrangement along with other information on irrigations practices for desert trees can be found at Irrigation Practices for Desert Trees.
Prune as needed to reinforce the structure and form of the tree. Periodic thinning is the most desirable method of pruning. Avoid hedging or heading back desert species, as this will only stimulate excessive branching. Do not remove more than 30% of the canopy during the summer as this can lead to sunburn injuries that can later be invaded by wood boring insects. Always use clean, sharp tools that are cleaned regularly in a 10% solution of bleach. For detail pruning guide see Pruning Desert Trees.
Periodically insect pests can be a problem on some desert trees. On young trees, insect infestation can slow typical seasonal growth. Inspect trees during the growing season for common garden sucking insects such as aphids, thrip, whiteflies or psyllids. During dry months, (May and June) in dusty conditions, spider mites can appear. Monitor for infestation and apply controls as needed. Spray applications of water or water and Safer Soap give short-term control (3 to 7 days) for small insect population. For heavy infestation or longer control use federally registered insecticides. A contact insecticide application will kill existing adults. An application with a systemic soil drench will provide 8 to 12 weeks control for any post application insect hatchings or migration of insects. Before using pesticide for the first time or on new plants or cultivar, treat a few plants and check for phytotoxicty. Always read label and follow label instruction before using pesticides. For pesticide control recommendations contact a licensed pest control advisor.
The information provided here was gathered from research literature published by the University of Arizona, other professional landscape and horticulture organizations and our experience at Arid Zone Trees. Always consult local landscape experts for recommendations for your specific area.