There are records of this cultivated "lemon mint" from FLEM (B) and perhaps BOYL (S. Studlar, pers. comm.), but not clearly naturalized. Although citrata has often been considered of hybrid origin from aquatica and spicata, its treatment remains somewhat controversial. Stace (1997) treated X citrata as a variety of X piperita; Kartesz (1999) and others have included it under aquatica; Tucker & Naczi (2007) and W have treated it as a variety of aquatica. Tucker and Naczi noted that most plants appear to be male sterile forms of aquatica (which has globose to ovoid heads), and may be named var. citrata (Ehrh.) Fresen., but these can cross with some forms of X piperita.