Cenizo (Leucophyllum frutescens)
Purple sage, Texas ranger, Texas barometer bush, Texas silverleaf, Texas sage
Native to southern NM and southern TX, and Northeastern Mexico. But used as a landscaping plant everywhere in the southwest. In Phoenix, you'll find hedges of them in front of every other strip mall and gas station.
In traditional medicine, it was used as a cold and flu tea, to stimulate sweating, break a fever, and as a mild sedative.
It is also used as just a plain old sipping tea, for its pleasant flavor.