With its lush green
foliage and conspicuous ½" long bright white thorns, A.
constricta is a study in visual contradiction, being at once
inviting and cautioning not to come too close. In summer the
finely divided (4 to 16 pairs of leaflets), lush green foliage
stands out against the gray to mahogany-brown bark. Thorns are
borne in pairs and originate at leaf nodes along branches.
Thorns are bright white and easily visible, adding to the
interesting texture of the tree's canopy. Yellow-orange,
fragrant, ball-shaped flowers first appear in spring and again
in late summer through the fall months (depending on seasonal
rains). Pods are 4" long, curved, reddish brown in color and
constricted or narrow between each seed. Trees are cold hardy to
0 degrees F and are both drought and cold deciduous.
Native to Arizona, and
Sonora, Mexico, it is found at elevations from 0 to 1800 feet,
along washes and arroyos where runoff compensates for the lack
of rainfall. In these natives setting it grows at a moderate
rate to a large shrub or small tree. In its natural habitat you
may find the tree unarmed. In the landscape, reports suggest a
range of mature sizes from 10 to 18' tall and as wide. They can
be grown in a spreading shrub form or pruned into graceful
single or multiple trunk specimens. White Thorn Acacia will
tolerate shallow, alkaline soils but will thrive in full sun and
well-drained soils. Established trees can be naturalized to
survive on annual rainfall in most desert locations but are most
lush and produce more flowers if irrigated deeply once a month
during spring and summer.
The Seri Indians used the
leaves, mashed seeds and roots of A. constricta for
stomach ailments, skin rashes and medicinal teas.
With a form and stature
similar to A. smallii,
White Thorn makes an excellent accent tree with its form, color
and fragrant flowers. Specimens can be planted singly or in
small groupings. Planting in combination with semi-evergreen
trees and shrubs will soften the visual impact of White Thorn
Acacia when it is dormant. They are also used to replant
disturbed desert or as a transition tree between landscaped
areas and the surrounding desert. Trees planted close together
will form a loose, informal hedge that provides screening and
security.