Jerusalem Thorn (Parkinsonia aculeata) - a Texas Tree for Dry Conditions
Jerusalem Thorn, Parkinsonia aculeata
(courtesy Texas Native Tree Gallery)
It was very noticeable here in Central Texas when the severe drought took effect during the summer of 2011, that local Jerusalem Thorn (Parkinsonia aculeata) trees were as bright green and "thrifty" as ever, while all around them other shrubs and trees were visibly browning or actually dying. In these uncertain days, when the prospect of little natural rainfall and water rationing are frequently mentioned, it is natural to wonder what usually overlooked native species might be good to introduce into the landscape.
Parkinsonias have been widely utilized in the drier areas of the Southwest for many years, especially as courtyard trees. Because of the small and scanty nature of their leaves, the shade beneath them is quite airy and light, so that containers of other plants placed underneath are both sheltered by light shade and able to absorb enough sunshine to function well. Parkinsonias can be quite decorative in the landscape when completely smothered with yellow blooms, followed by interesting dangling green seed pods.
Typically, Jerusalem Thorn is quite drought-resistant, capable of growing to a tree form 30 feet in height in an environment with plenty of moisture and good soil, or remaining shrubby where water is at a premium or soils are difficult. It prefers full sun, and is not particular about soil types. Zigzagging stems and multiple trunks make this a plant of interesting character. In keeping with its name, there are thorns, which are fairly typical of desert plants.
Flowers are yellow-orange and fragrant, up to 3/4th inch in diameter, growing in groups of up to 8 or more from a long stalk. There are five sepals and five petals to each bloom, with one longer petal of a stronger yellow color with purple spots at its base. The flowering period begins in the spring, but can repeat after good rains throughout the summer. The flowers are pollinated by bees, and the pollen provides bee food.