Acacia aneura (Mulga) In a landscape palette with a limited number of evergreen trees, Acacia aneura is a welcome addition to desert landscapes. Acacia aneura is native to all mainland states of Australia, where it grows in low rainfall areas and in most soils, including clay. The common name, Mulga" is an Australian Aboriginal word that means dream seed, both the tree and it’s seed are part of their mythology. The tree has a moderate growth rate with a mature height of 14’ to 18’. It grows well in a variety of settings but prefers full sun and well draining soils. The densely arranged needle-like, silver -gray phyllodes (leaves) give the canopy an airy, lacy quality that contrasts with the dark reddish brown branches. The canopy can extend to the ground. Typically bottom branches are trimmed to expose the trunk(s) and give the tree an umbrella form.

Acacia aneura is unusual in that it has an open flowering cycle. The trees produce small, sulphur yellow, rod shaped flowers about 3/4" long. Tan pods (1" to 1 1/2") mature from these flowers and are ultimately dropped. Once this flowering cycle is complete another one begins. Trees may produce 3 to 4 flower cycles per year with the heaviest flowering usually occurring in the spring or following summer rains. The bright yellow flowers in combination with the silver-gray leaves make Acacia aneura a striking accent tree in the landscape. It is also used as a hedge or screen planting and can be used in small groupings. Encouraging a more shrub-like growth habit, by reducing or eliminating pruning, is more desirable in hedge and shrub applications. Because trees are damaged by water saturated soils it is not recommended for planting in turf areas or with an understory of high water demanding plants.

Reports indicate the Acacia aneura is hardy to about 20 to 27 degrees F. Our experience in Phoenix is that the trees survive normal" winters. This Australian native has clearly found a home in the desert southwest.

Acacia berlandieri (Guajillo) With one important exception the Texas native Acacia berlandieri (or Guajillo) shares many characteristics with the popular Lysiloma thornberi (or Fern of the Desert). Both have lush green lacy, fern like leaves and graceful curved branching patterns; both produce creamy white ball flowers in spring and are essentially thornless. The great advantage of the Guajillo is that it is cold hardy to about 10 degrees F. In typical Phoenix winters it retains most of its leaves. The common name of this tree Guajillo" is a Mexican word that means foolish or funny, and was referred to by this name because it sometimes grows in funny or unusual places. The tree grows at a moderate rate in an array of well draining soil types and settings. Mature trees grow to about 9’ to 15’ tall and about as wide. Trees prefer full sun but will tolerate partial shade. A natural tendency toward multiple trunk growth coupled with a generally shrub-like growth habit means that young trees will require some pruning and shaping to achieve desirable form. Cream colored, mildly fragrant flowers are borne in clusters along the branches in early spring. Flowers produce broad, elongate dark brown seed pods (very similar in appearance to those found on Lysiloma). Pods split to release seeds and most are eventually dropped. Pod litter can be a problem in years with heavy seed crops. Acacia berlandieri adds a soft lush quality to the landscape and mixes well with a variety of desert trees and shrubs. Its semi-evergreen nature makes it an excellent complement to trees and shrubs that may be more deciduous in winter. Its smaller stature makes it a good accent tree or planted with taller maturing trees to create a landscape screen. Acacia berlandieri is an excellent alternative to Lysiloma in those settings where cold hardiness is an issue or where less deciduous trees are needed in desert landscapes.