1850, from sage (n.1), to which it has no biological affinity, + brush (n.2). Said to be so called for resemblance of its appearance or odor.
Sage-brush is very fair fuel, but as a vegetable it is a distinguished failure. Nothing can abide the taste of it but the jackass and his illegitimate child, the mule. ["Mark Twain," "Roughing It"]
