The palo verde tree is the herald of spring for many in the southwestern United States, displaying huge numbers of bright yellow flowers. A low-growing and shrubby tree, the palo verde is popular as a landscape plant for its floral display and its open, airy canopy of bright green leaves and curious green trunk. A true desert plant, it requires little in the way of cultivation, given the right growing conditions.
Palo verde trees are originally from the Sonoran and Mojave deserts of southwestern United States and Mexico and in Baja California, and are now found throughout the southern parts of the country. The plant will grow in elevations of 4,000 feet and is hardy to temperatures in the low teens in hardiness zones 8 through 10. Palo verde is frequently found in residential plantings as a specimen and shade tree, and along roadways and in parks in municipal landscapes.
Trunk, Bark and Branches
Palo verde trees can grow to 30 feet tall and can spread just as wide, and they can be very shrub-like in appearance. The trunk can be a single leader trunk or several trunks that support many limbs that radiate outward and upward from the center of the plant. The plant is finely branched with many twig and stems. The bark is usually smooth and green, turning light to dark gray with a rough texture as the tree matures. The branches and stems are green and may possess short, blunt spines.
The leaves of the palo verde tree are compound with a central stem and small oval leaflets up to 1 inch in length. The leaflets are flat, thick and somewhat succulent and grow opposite each other, four to 12 on a stem. Their color is bright green and can have a blueish cast at times.
The flowers of the palo verde tree appear early in spring. The entire tree will be conspicuously covered with bright yellow flowers that form in clusters along the stems of the plant. Each flower resembles a pea blossom and has large, bright red anthers projecting from the center of each flower.
The fruit of the palo verde tree forms as a large, flattened seed pod with up to three flat, round, brown seeds inside. The pods start out green, then turn brown, and eventually bleach to white as they mature. Each pod is from 2 to 3 inches long.
The tree needs full sun with plenty of reflected heat from the ground. It is extremely drought tolerant and requires infrequent but deep irrigation, once or twice a month. Palo verde trees are tolerant of a range of soil conditions but need good drainage to grow well. They can be propagated from seeds, if the hard seed coat is first treated with acid or physically opened. The tree can produce considerable litter and can be messy. Pruning to shape is possible, though rarely necessary.