White-thorn acacia (also known as mescat acacia or huisache) is a shrub, typically growing to 6 feet tall (occasionally a tree to almost 20 feet tall) and is evergreen warm areas, partly deciduous in colder or more arid conditions. As the common name implies, it is armed with many small white thorns. Fragrant yellow puffball flowers occur in late spring, and again in the summer. Of all our native shrubs in the Tucson vicinity, this one can be one of the most attractive. On irrigation plants become very lush and large. Being native here it is, of course, hardy (to about 10 degrees F.). Spination is variable. Sometimes plants will be thornless while others, very spiny. Pods that emerge after blooming will twist upon maturity. Plants have been recorded to live about 70 years in the wild.
There is a variety called Acacia constricta var. paucispina that is supposed to be spiny with less glandular leaves. Many reject this taxon because spination is variable whether or not leaves are glandular. There are a few shrubs that resemble Acacia constricta. The apparently related Acacia neovernicosa, a supposed Chihuahuan Desert version of white thorn, is more airy looking with less pinnae and very resinous foliage. Other shrubs only slightly resemble white thorn.
Give full to part sun. After some time plants can tolerate living on just rainwater, however it takes a few years to establish plants before letting them exist this way. Plants on irrigation always look great while plants living on rainfall will go dormant, dropping leaves and sometimes sustaining stem dieback as they do in nature. A light fertilization will make plants remarkably lush and fast growing. This plant really needs very little care, however. Propagation is from seed. Caterpillars may defoliate plants in spring, though leaves emerge quickly again shortly thereafter. Occasionally plants may be infested with mistletoe.
The Seri indians used the crushed seeds and leaves to relieve upset stomach and diarrhea. The same, powdered, has been used to treat rashes, and roots have been used to make a medicinal tea.
Acacia constricta occurs throughout much of Mexico and into the southwestern United States of Arizona, New Mexico, and Texas. Personally it is one of my favorites, as a foundation in both the urban landscape, as in nature where it occurs and provides a great foundation, aesthetically and ecologically.
Some Pages with white-thorn:
The Fire Effects Information System (FEIS) on Acacia constricta
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