[Wikipedia] Etymology: The specific name farnesiana honors Odoardo Farnese (1573 - 1626) of the notable Italian Farnese family, which after 1550, under the patronage of Cardinal Alessandro Farnese, maintained some of the first private European botanical gardens in Rome, the Farnese Gardens, in the 16th and 17th centuries.
This acacia was first described from these gardens, imported to Italy from Santo Domingo, in what is now the Dominican Republic.
Analysis of essences of the floral extract from this plant, long used in perfumery, resulted in the name for the sesquiterpene biosynthetic chemical farnesol, found as a basic sterol precursor in plants, and cholesterol precursor in animals.
The name huisache of Mexico and Texas is derived from Nahuatl and means "many thorns". The Australian name needle bush came about because of the numerous thorns distributed along its branches. (link added by Mary Ann Machi)