Edward F. Gilman, Dennis G. Watson, Ryan W. Klein, Andrew K. Koeser, Deborah R. Hilbert, and Drew C. McLean
Introduction
Loose, flowing, delicate leaflets, a light, airy, low-branching growth habit with pendulous branch-tips, and a profusion of small, slightly fragrant, bright yellow blooms combine to create this popular, small landscape tree. Quickly reaching a height of 15 to 25 feet with a similar spread, this multitrunked deciduous tree is actually much stronger than its fragile appearance would suggest. Branch bark often remains bright green even on several-year-old limbs.
Figure 1. Full Form - Parkinsonia aculeata: Jerusalem-thorn Credit: UF/IFAS
Origin: native to the southwestern United States, Mexico, and tropical Americas
UF/IFAS Invasive Assessment Status: invasive and not recommended (North, Central, South)
Uses: street without sidewalk; specimen; parking lot island < 100 sq ft; parking lot island 100-200 sq ft; parking lot island > 200 sq ft; urban tolerant; highway median
Figure 2. Range
Description
Height: 15 to 20 feet
Spread: 20 to 25 feet
Crown uniformity: irregular
Crown shape: vase, spreading
Crown density: open
Growth rate: fast
Texture: fine
Foliage
Leaf arrangement: alternate
Leaf type: odd-pinnately compound; occur in pairs of 1 to 2 primary leaflets and made up of 20 to 30 pairs of secondary leaflets
Leaf margin: entire
Leaf shape: linear, oblanceolate
Leaf venation: none, or difficult to see
Leaf type and persistence: deciduous
Leaf blade length: primary leaflets are8 to 16 inches; secondary leaflets are ¼ inch
Pest resistance: free of serious pests and diseases
Use and Management
Be sure to purchase trees with a well-developed central leader and upright branches for street and parking lot plantings to allow for clearance for vehicles. This can be a tough chore as branches weep toward the ground as they spread from the tree so older specimens can be wider than tall. Open-grown trees are beautiful if left unpruned, forming a fountain of fine texture. The stems are armed with short, sharp spines and the trees should be located where they will not injure passersby.
Thriving in full sun on any well-drained soil, Jerusalem-thorn will tolerate heat, drought, alkaline soil, and salt but not wet, soggy soil. It will grow in clay only if it drains very well. In spite of its rapid growth rate, it has strong wood, withstanding harsh winds with ease due to the open growth habit. However, the trees have a short life, approximately 15 to 20 years. Poor drainage may account for short life on many sites, so locate it accordingly in areas where soil is never wet for more than an hour or two. The bark is thin and easily injured and the tree appears to compartmentalize decay poorly. Locate the tree properly and design the site to minimize trunk injury.
Adapted to arid regions, Jerusalem-thorn is one of the best choices for hot, dry locations and its salt-tolerance makes it ideal for seaside plantings. The light shade afforded by the fine-textured foliage allows lawns to thrive beneath this tree and its small size allows a multitude of applications, from specimen, parking lot, median, or street tree, set back from the road or walk. There are reports of the plant escaping cultivation in some locations along the gulf coast.
Propagation is by seed.
Pests
Some pests of Jerusalen Thorn are scales and thorn bugs, but none are serious.
Diseases
One disease that infects this tree on wet soils is root rot but none are serious on other sites.
Witches-broom occasionally causes a proliferation of branches forming tight heads of foliage.
Reference
Koeser, A.K., Friedman, M.H., Hasing, G., Finley, H., Schelb, J. 2017. Trees: South Florida and the Keys. University of Florida Institute of Food and Agricultural Sciences.
