Scientific: Parkinsonia microphylla (formerly Cercidium microphyllum)
Common: foothills or little leaf palo verde, yellow palo verde
Family: Fabaceae (Leguminosae)
Origin: Widely dispersed within upland foothill subdivision of Sonoran Desert in eastern California, Arizona, and into Sonora and Baja California.

Pronounciation: Par-kin-SONE-ee-a my-crow-FIL-la

Hardiness zones:
Sunset 10-14, 18-20
USDA 9-10 (arid regions only)

Landscape Use: Xeric and/or native desert gardens as a small multi-branched tree or large background shrub.

Form & Character: Deciduous tree, stiff, rounded and spreading, open with intricate terminal branching, arid.

Growth Habit: Monoecious, spiny shrub to small tree, partially deciduous with moderately slow growth to 15 to 25 feet in height with equal spread depending on site water availability.

Foliage/texture: Tiny pinnately compound leaves, 4 to 8 pairs leaflets, short terminal spur branches that growth to a stiff and spine like tip, leaves, stems and branches are all medium to yellowish green, photosynthetic; fine texture.

Flowers & fruits: Pale yellow pea-shaped flowers followed by short, brownish pods in mid summer that abscise all at once.

Seasonal color: Pale yellow flowers in late May just after P. florida and P. praecox.

Temperature: Tolerant

Light: Full sun

Soil: Tolerant, but grows best in a coarse, well-drained to gravelly soil.

Watering: Little to none once established, though it will grow faster with supplemental water.

Pruning: Prune only if necessary by elevating canopy base, train early to avoid large wounds.

Propagation: Seed, acid scarification of seeds in 95% sulfuric acid for 30 min to 1 hr followed by a 15 minute rinse in cool to tepid water. Sow immediately thereafter.

Disease and pests: Palo verde borer, see other Parkinsonia fact sheets for management of this insect pest. Parkinsonia microphylla and Parkinsonia praecox are subject to a condition called "trunk blister" in Phoenix urban landscapes, the casual agent as yet has not been identified.

Additional comments: Stiffer, smaller and less refined compared to its 'big brother', P. florida. In the nursery trade not widely available because of slower growth, smaller size and more deciduous habit.

Foothills palo verde is quite at home naturalizing anywhere in the Phoenix area where there's a bit of topography.