Accession Count: 2

Acacia rigidula

Common Name: blackbrush acacia
Family Name: Fabaceae
Botanical Name: Acacia rigidula
Synonyms:
Botanical Synonyms: Vachellia rigidula
Family Synonyms: Leguminosae
Sub Species:
Variety:
Forma:
Cultivar:
Characteristics: Acacia ridigula is a slow growing, vigorous and long-lived deciduous shrub with rigid, pale and thorny branches that display rich, dark-green foliage. The 2 cm (~1 inch) long leaves are pinnately compound and have elongated, 1/2 cm (1/4 in) oval shaped leaflets arranged in pairs.  Fragrant, pale yellow flowers, which appear in early spring and summer (March-May), are borne on 5 cm (2 in) long rod-shaped inflorescences which densely cover the tree canopy throughout the blooming season (3, 6).
Compound: Aca rig
Geographic Origin: Texas/Northern Mexico
Ecozone Origin: Palearctic
Biome Origin:
Natural History: A. rigidula otherwise known as the “blackbrush acacia” is native to desert regions of the southeast US and northeastern Mexico (1). Its distribution spans regions of south and east Texas, to northern regions of Mexico including Nuevo Leon and further south to Tamulipas and San Luis Potosi (3). It is common for this plant to be found in rocky limestone hillsides at elevations between 350-550m (1100-1800 ft) (3). 
Cultivation Notes:
This species is naturally grows as a large shrub or small tree (2). It is not commonly propagated through grafting or cuttings as it is fairly easily propagated through seeds (3). In the landscape, it prefers full sun exposure and loose, well-drained sandy to loamy soils. The blackbrush acacia is drought tolerant and thrives even with minimal watering - requiring water only once a month most of the year (6).

Ethnobotany:
Blackbrush acacia, was used traditionally by native Americans medicinally (4). Tea can be made from the flowers have sedative properties. The roots of the plant can also be used to make a tea that has been used to treat sore throats, coughing, and mouth inflammations (2). Consumption of the seeds purportedly alleviates stomachaches and treats diarrhea. Leaves ground into powder are used to stop bleeding, relieve chafed skin, or diluted in water and used as an antimicrobial wash (4). Commercially, the plant is used to derive phytochemical stimulants such as amphetamines, used in dietary supplements and weight loss medications (5). This plant also provides food for some wild animals. While it is not the preferred source of food for deer and other animals, but it can be consumed when other food resources are scarce (1). Its flowers also provide nectar for bees and butterflies (3). With pruning early on, the normally large shrubby plant can become a small tree (6). As such, it is an excellent, low water use shade tree for the landscape. It can serve as a physical barrier or screen as a shrub but is also outstanding when displayed by itself as a specimen tree in the landscape. Best suited for transition and arid zones in xeriscapes, the dark, green foliage of A. rigidula provides a striking contrast to the pale and light-colored plants typical in desert landscapes. 


Height: 16 - 20 feet
Width: 11 - 15 feet
Growth Rate: Slow Growing
Grow Season: ForeSummer
Flower Season: Spring
Color: Yellow
Function: Screen
Spread: Non-spreading
Allergen: Non-allergenic
Invasive: Benign
Toxicity: Benign
Hardy: Hardy
Water Use: Low water Use

Citations:

1. http://www.mswn.com/media/info_sheets/acacia_rigidula.pdf. Retrieved April 23, 2015. 

2. http://aggie-horticulture.tamu.edu/ornamentals/nativeshrubs/acaciarigid.htm. Retrieved April 23, 2015. 

3. http://www.wildflower.org/plants/result.php?id_plant=ACRI. Retrieved April 23, 2015. 

4. http://wc.pima.edu/~bfiero/tucsonecology/plants/trees_wta.htm. Retrieved April 22, 2015.

5. http://www.webmd.com/vitamins-and-supplements/news/20150407/bmpea-acacia-rigidula-supplments. Retrieved April 23, 2015. 

6. Mielke, Judy. Native Plants for Southwestern Landscapes. University of Texas Press, 1993.

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Acacia rigidula