A distinctive native pepperweed. Notice the white, club-like hairs on the stems (close-up in 2nd image). Known from "dry grassy places" in the Trans-Pecos.
The Brassicales are an order of flowering plants, belonging to the eurosids II group of dicotyledons under the APG II system. One character common to many members of the order is the production of glucosinolate (mustard oil) compounds. Most systems of classification have included this order, although sometimes under the name Capparales (the name chosen depending on which is thought to have priority).