Cercidium microphyllum (Parkinsonia microphyllum) Foothill Palo Verde
Foliage: Deciduous
Mature Height: 12’ - 20’
Mature Width: 12’ - 25’
Growth Rate: Slow
Hardiness: 15 degrees F
Exposure: Full Sun
Leaf Color: Green
Shade: Filtered
Flower Color: Pale to Bright Yellow
Flower Shape: Funnel Shaped Petals
Flower Season: Spring
Thorns: Yes
Propagation Method: Seed
Sizes Available: #25, #45, and 48"
FOOTHILL PALO VERDE: Foothill Palo Verde is the smallest of the Palo Verdes, typically maturing to 12' to 20' tall and 12' to 20' wide. It is native to the American southwest, Baja and Sonora, Mexico at elevations from 500 to 4000'. It grows on rocky slopes, desert foothills and mesas. Leaves are yellow green and very small (the Latin species name microphyllum means tiny leave). Half inch pale to bright yellow blooms appear beginning in April or May. Flowers usually last until the onset of 100 degree temperatures.
Established trees in the landscape can survive on seasonal rainfall. The trees are hardy to 15 to 17 degrees but like Ironwoods will not tolerate excessive irrigation. All branches, mature and immature, end in a sharp, rigid spine. These spines limit the use of Foothills around walkways and play areas. Leaves are widely distributed along these branches giving the leaf canopy a pale green, transparent quality. Drought or severe cold will cause leaf drop. Trees will need some pruning to shape the canopy and accentuate the trunk structure. Most specimens are multiple trunked. Some single trunked trees are produced in the nursery.
The curved, gnarled trunks give Foothill Palo Verde a sculptural quality. They are often used at entry monuments, as focal point single specimens. They can also be used as transition trees back to native desert, as perimeter plantings or as a component of a mixed desert planting. While trees can survive on rainfall, monthly irrigations make for a more lush appearance. Again, as with Ironwoods, Foothills will not tolerate over irrigation.
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.