Scientific: Acacia saligna (Synonyms: Acacia bracteata, Acacia cyanophylla, Acacia lindleyi, Mimosa saligna, Racosperma salignum)
Common: blue-leaf wattle, weeping wattle, golden wreath wattle tree, Port Jackson wattle
Family: Fabaceae (Leguminosae)
Origin: Predominately native to southwestern Australia
Invasive Alert: Blue leaf wattle is an invasive species in warm temperate and semi-arid regions worldwide forming dense monospecific stands.
Pronounciation: A-KAY-sha sa-LIG-na
Hardiness zones
Sunset 8, 9, 13-24
USDA 9-11
Landscape Use: Large visual or noise screening plant, small spreading tree casting a moderately dense shade, background screen, oasis and xeric landscape design types.
Form & Character: Upright to billowing and spreading, dome-like, pendulous, marginally graceful, semi-symmetrical, aggressive, awkward.
Growth Habit: Evergreen, woody, broadleaf perennial large shrub or small tree, vigorous growth rate, spreading to pendulous, 20- or 30-feet tall with a greater spread, a nitrogen-fixing legume.
Foliage/Texture: Lanceolate, long, blue-green falcate phyllodes to 6- to 12-inches long, juvenile phyllodes are especially large. Trunk generally grayish brown and smooth when young becoming roughened with age, weak and brittle wood; medium texture.
Flowers & Fruits: Numerous 1/2-inch wide axillary yellow flowers in racemes; fruits are a flattened brown pod that grows to 5-inches long and are somewhat constricted between seeds.
Seasonal Color: Blue-leaf wattle produces a surprisingly wonderful canopy of yellow flowers in March.
Temperature: Hardy to 19oF. Tolerant of high desert heat.
Light: Full sun required, no shade.
Soil: Tolerant of all but most alkaline soils.
Watering: Infrequent deep irrigations; use water to control growth rate. High water applications means rank growth.
Pruning: Must elevate canopy base if used as multiple-trunk tree to overcome pendulous habit.
Propagation: Seed, scarify in 95% sulfuric acid for 30 minutes then wash on running tepid water for 30 minutes.
Disease and Pests: Numerous root rot pathogens infect plant if soil is excessively wet.
Additional comments: The careful planning and use of blue-leaf wattle is critical because of its wide-spreading habit and pendulous umbrella-like form (takes up A LOT of space). If one naively plants this spreading small tree in a
small space, then its future maintenance requirements (pruning) will be annoyingly high. ALWAYS keep in mind that this is NOT a street tree or a tree to be planted in high traffic locations. It is also relatively short lived and weak wooded, which means that catastrophic limb failure during high wind events can occur....especially if this tree is over watered.
Acacia saligna is valued as tree for livestock fodder and soil conservation efforts (stabilize damaged soils and prevent erosion).
The final word: Because of the issues so succinctly articulated above, the local popularity of blue-leaf wattle as a small tree for Phoenix landscapes came and went during the early 1990s. Today, blue-leaf wattle is a real landscape 'loser', and has now been relagated to the 'bone pile' of Phoenix landscape trees.
