Parkinsonia aculeata, palo verde, Jerusalem thorn, jelly bean tree, palo de rayo, retama, 25-100 seeds 2023
Parkinsonia aculeata is a species of perennial flowering tree in Fabaceae family. Common names include palo verde, Mexican palo verde, Parkinsonia, Jerusalem thorn, jelly bean tree, palo de rayo, retama, Horse bean, Lluvia De Oro.
The genus name Parkinsonia honors the English botanist John Parkinson (1567–1650), while the species Latin name aculeata refers to the thorny stem of this plant.
The name "Jerusalem thorn" stems from a mistranslation of the Spanish/Portuguese word girasol ('turning toward the sun').
Parkinsonia aculeata may be a spiny shrub or a small tree. It grows 2 to 8 m (6.6 to 26.2 ft) high, with a maximum height of 10 metres (33 ft). Palo verde may have single or multiple stems and many branches with pendulous leaves.
The branches grow double or triple sharp spines at the axils of the leaves. The flowers are yellow-orange and fragrant, 20 mm (0.79 in) in diameter. The flowering period is in the middle months of spring (March–April or September–October). The flowers are pollinated by bees. The fruit is a seedpod, leathery in appearance, light brown when mature.
P. aculeata is a major invasive species in Australia, as it is listed as a Weed of National Significance and is ranked as Australia's worst weed. It is also a major problem in parts of tropical Africa, Hawaii, and other Islands in the Pacific Ocean.
P. aculeata is native to the southwestern United States and northern Mexico south to Galapagos Islands and northern Argentina. It has been introduced in Africa, Australia, India, Pakistan and Spain.
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 (sand dunes, clay, alkaline and chalky soils, etc.), at an altitude of 0–1,500 metres (0–4,921 ft) above sea level.
Parkinsonia aculeata has a hard seedcoat and benefits from scarification before sowing to speed up germination. This can usually be done by pouring a small amount of nearly boiling water on the seeds (being careful not to cook them!) and then soaking them for 12 - 24 hours in warm water. By this time they should have imbibed moisture and swollen - if they have not, then carefully make a nick in the seedcoat (being careful not to damage the embryo) and soak for a further 12 hours before sowing. Sow the seed in a sunny position in a nursery seedbed or in individual containers. A high germination rate can be expected, with the seed sprouting within 8 - 16 days. The plants should be ready to plant out 8 - 10 months later.