Condalia hookeri

Condalia hookeri, called the Brazilian bluewood, is a widespread species of flowering plant in the family Rhamnaceae, native to Texas and eastern Mexico. It is a thorny shrub or small tree reaching 6 m (20 ft) but usually much shorter. Typically it is found growing in marginal habitats such as limestone slopes, sandstone bluffs, lunettes, shell ridges, juniper-dominated woodlands, or along watercourses, often in clayey or sandy soils, at elevations from 10 to 400 m (30 to 1,300 ft). It may come to dominate an area as a thorny scrubland....read more on Wikipedia.