Mexican oregano (Lippia graveolens) is the citrusy, boldly aromatic herb that anchors the cooking of Mexico and the American Southwest — the "oregano" of salsas, chilis, moles and pozole. Despite the shared name and a comparable carvacrol punch, it is not true oregano at all but a shrub of the verbena family, and beneath its familiar warm, phenolic bite runs a bright citrus-and-anise lift that Mediterranean oregano lacks.