Mexican Palo Verde

Appearance

"Parkinsonia aculeata" may be a spiny shrub or a small tree. It grows 2 to 8 m high, with a maximum height of 10 metres. Palo verde may have single or multiple stems and many branches with pendulous leaves. The leaves and stems are hairless. The leaves are alternate and pennate. The flattened petiole is edged by two rows of 25–30 tiny oval leaflets; the leaflets are soon deciduous in dry weather leaving the green petioles and branches to photosynthesize.

The branches grow double or triple sharp spines 7–12 mm long at the axils of the leaves. The flowers are yellow- orange and fragrant, 20 mm in diameter, growing from a long slender stalk in groups of eight to ten. They have five sepals and five petals, four of them clearer and rhomboid ovate, the fifth elongated, with a warmer yellow and purple spots at the base. The flowering period is in the middle months of spring. The flowers are pollinated by bees. The fruit is a seedpod, leathery in appearance, light brown when mature.

Naming

The genus name "Parkinsonia" honors the English botanist John Parkinson, while the species Latin name "aculeata" refers to the thorny stem of this plant.

Distribution

"P. aculeata" is native to the Sonoran and Chihuahan Deserts of southwestern United States, and northern Mexico as well as the Galápagos Islands. Its native range has expanded over the last several decades into the. It has been moved by humans into the Caribbean, South America south to northern Argentina, and Hawai'i. It has been introduced in Europe and it is widespread in Australia. This thin barked species does not become established in areas where weather dips below 20 degrees F. It has expanded into Southern California as far north as San Bernardino County.

Habitat

"Parkinsonia aculeata" has a high tolerance to drought, simply attaining shorter stature. In moist and humus-rich environments it becomes a taller, spreading shade tree. This plant prefers a full sun exposure, but can grow on a wide range of dry soils, at an altitude of 0–1,500 metres above sea level.