Size: Generally about 16 feet (4.9 m), rarely 25 feet (7.6 m), slightly smaller than Blue Paloverde.
Growth Form: Yellow Paloverde is a relatively small spinytree or shrub that is heavily branched with an open crown, the bark is smooth, yellow-green and has the ability to photosynthesize.
Leaves: Yellow Paloverde has green or yellow-green leaves that are deciduous during extreme heat and drought periods; the leaves are pinnatelycompound and generally absent most of the year.
Flower Color: Yellow Paloverde flowers are mostly yellow, about 1 inch (2.5 cm) across, these flowers are smaller and paler than those on the Blue Paloverde; the bannerpetal is cream or white as shown above, and the fruit is a short, soft pod (legume) about 2 to 3 inches (5 - 7.6 cm) long, constricted (unlike the Blue Paloverde) between the seeds.
Flowering Season: April and May.
Elevation: Below 4,000 feet (1,219 m).
Habitat Preferences: Dry rocky hillsides and mesas, less common in washes than Blue Paloverde which requires more regular water.
Recorded Range: Although common where found, Yellow Paloverde is relatively rare in the United States where it occurs only in Arizona and California. In Arizona it is found primarily in the central and west half of the state and in California it is an uncommon plant in San Bernadino County.
Threatened/Endangered Information: In Arizona, Yellow Paloverde, Parkinsonia microphylla, is "Salvage Assessed, Harvest Restricted" (A permit from the Department of Agriculture is necessary to transport this species off private property.)
Genus Information: In North America, USDA Plants Database lists 4 species and 6 accepted taxa overall for Parkinsonia. Worldwide, World Flora Online includes 13 accepted species names for Parkinsonia.
In the Southwestern United States: Arizona, California and Texas each have 3 species of Parkinsonia, Nevada has 2 species and New Mexico and Utah each have 1 species. Data approximate, subject to revision.
Comments: Yellow Paloverde is a common cultivated ornamental plant in desert landscapes although it is somewhat frost tender. Yellow Paloverde trees live more than 70 years of age. Both the Yellow and Blue Paloverde trees are very slow growers. The type specimen for Parkinsonia microphylla is from the Colorado and Bill Williams Rivers.
Yellow Paloverde is one of the most common trees of the Sonoran Desert where it is both an indicator species and a co-dominant plant along with other co-dominant species including Creosote-bush (Larrea), Triangle Bursage (Ambrosia), Brittlebush (Encelia), Ocotillo (Fouquieria) and Wolfberry (Lycium). This community is sometimes called the Paloverde, Bursage desert scrub community.
Key distinguishing features that are generally, not always accurate separating 3 similar species of local Paloverde trees is the color of the large banner or standardpetal as follows;
Jerusalem Thorn has a red, brown or a few red splashes on the bannerpetal.
Parkinsonia microphylla has 1 inch (2.5 cm) attractive flowers, the flowers, their seeds and plants may be visited by hummingbirds and/or small mammals including rodents and granivorous birds in search of food, nectar and protection through cover.
Certain wildlife species including Jackrabbits may browse on the stems and small mammals may forage on the seeds and seed pods during drought times when there is little else to feed on.
Beneficial Value to Butterflies, Honey Bees and Insects
Parkinsonia microphylla has attractive flowers, the flowers and their plants may be visited or used by butterflies, moths, flies, honeybees, native bees and other insects in search of nectar, food or shelter and protection.