Lemon verbena is a South American plant, Aloysia triphylla, a relative of Mexican oregano. The lemony flavor of its leaves comes from the same terpenes, collectively called citral, that flavor lemon-grass; other terpenes lend a flowery note.
From the book On Food and Cooking (2nd edition) by Harold McGee. © 2004 Harold McGee. By permission of Scribner, a division of Simon & Schuster, Inc.