Along the dry Pacific coastal plain, from the southern end of the Desierto Sonorense to the state of Guerrero, as well as on the northern Gulf Coast plain and in the northern Yucatán Peninsula, the predominant vegetation is thorn forest, composed of thorny bushes and small trees, including many acacias.

Some of this flora occurs naturally, some occurs on overgrazed grassland or abandoned slash-and-burn farmland.