Xeriscape Landscaping Plants For The Arizona Desert Environment
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Blackbrush Acacia, Acacia rigidula

Blackbrush Acacia, Acacia rigidula; Photo October 11, 2006. Boyce Thompson Arboretum

Blackbrush Acacia Leaves Acacia rigidula	Blackbrush Acacia Leaf Structure Acacia rigidula
Blackbrush Acacia Stem Acacia rigidula	Blackbrush Acacia Seed Pods Acacia rigidula

Blackbrush Acacia Acacia rigidula Fabaceae Family ( Pea ) Blackbrush Acacia. Also called: Chaparro Prieto, Blackbrush Chaparro, Gavia. This thorny little tree or shrub possess white to light-yellow flowers that appear in cylindrical spikes; they can be so abundant that they literally dominate the branch. The leaves are alternate and compound, with two to four (rarely five) pairs of leaflets, and they possess straight spines. Most people, as well as bees, appreciate these lovely shrubs when flowering; they make especially good honey. Blackbrush is usually a muli-stemmed shrub or tree with numerous thorny branches sprouting from the base. It possess white to light-yellow flowers that appear in cylindrical spikes. It grows typically from three to fifteen feet high. Chaparro Prieto produces many white to pale yellow flowers from early March to mid - June. Small mammals and birds inhabit this plant for protection. This plant is often used in rock gardens, landscapes, or xeriscapes. Acacia rigidula (Black Bush Acacia) is a deciduous tree, native to western and southern Texas and a several northeastern Mexican states. In natural setting it is typically found on rocky hillsides and along canyon floors at elevations from 1100 to 1800 feet above sea level. It occurs as scattered individual plant and in clumps or thickets. Under natural growing conditions the tree matures to about 10 to 15 feet tall and as wide but will likely grow larger in landscape settings. Gavia has yellow to cream colored flowers arranged in 2 to 3 inch long, slender spikes appear from March to mid-June. Then slender pods about 3 inches long develop from these flowers. The tree is deciduous and the branches are armed with numerous thorns. Black Bush thrives in full sun and a variety of soil types and conditions including very poor calcareous (caliche) soils. Trees grow at a moderate to slow rate. Regular irrigation is needed at first but after it is growing for a few years it will survive on desert rainfall. However, monthly summer irrigation of the mature, established trees will optimize their growth and appearance. The unique charm of this tree, besides its modest statue, is its dark green, glossy, foliage, which is borne on stiff, densely packed, gray barked branches. Black Bush is an excellent screen, barrier, or foundation plant, or as a backdrop for other flowering plants or for erosion control. Specimens can be left as a large mounding shrub or pruned to a sculptural tree form that accents the contrast between green leaves and gray bark. It is slow growing; needs good drainage, tolerates a wide range of soils; low water use, and full sun, it is hardy to 20°. Often people confuse this tree with a mimosa. Acacias and mimosas are often so similar they are difficult to tell apart. But the key difference is in the flowers themselves: acacia flowers possess numerous (20-100) stamens, while mimosas possess 10 to fewer stamens per flower. And mimosa fruits (pods) are flattened and somewhat contorted. The nations largest Blackbrush tree is located in Casa Grande, Arizona. It is in the National Register Of Big Trees. It is over 26 feet tall and 29 feet wide. The second runner up is at Glendale, Arizona at Mountain States Nursery. Height: Normally, 3 To 20 feet tall; up to 18 feet wide. Bark: Grayish-brown, thin, smooth or scaly. Trunk: 3 to 10 inches in diameter. Twigs: Stiff, densely packed, gray barked branches. Flowers: Yellow to cream colored, very fragrant flowers arranged in 2 to 3 inch long, slender spikes. Blooming Time: Early March to mid - June. Leaves: Alternate and compound, with two to four (rarely five) pairs of leaflets, and they possess straight spines. Seeds: Slender pods about 3 inches long, dark brown or black, hard. Found: Native to West and South Texas; and Tamaulipas, Coahuila, and Chihuahua in Northern Mexico. Elevation: Below 1,800 Feet. Said to live up to 4,500 feet. Habitat: Ornamental in lower elevations or Arizona. Excellent for xeriscape landscaping. Miscellaneous: Photos Taken October 11, 2006. Boyce Thompson Arboretum. Not native to Arizona.