American Water Horehound, American Water-horehound, Cutleaf Water-horehound, Cutleaf Waterhorehound, Cut-leaved Water Horehound: Lycopus americanus (Synonyms: Lycopus americanus var. longii, Lycopus americanus var. scabrifolius, Lycopus sinuatus) - The calyx lobes are narrowly triangular, firm, and longer than the nutlets. Leaves tapering to a short petiole. Leaf margins irregularly cut deeply and sharply into the blade.
Western Water-horehound, Rough Bugleweed, Rough Water-horeound: Lycopus asper (Synonyms: Lycopus lucidus, Lycopus lucidus ssp. americanus, Lycopus lucidus var. americanus) - The calyx lobes are narrowly triangular, firm, and longer than the nutlets. Leaves sessile or subsessile, the base tapering gradually or abruptly to the stem. The leaf margins are coarsely but evenly toothed.
Northern Bugle-weed: Lycopus uniflorus (Synonyms: Lycopus uniflorus var. uniflorus, Lycopus virginicus var. pauciflorus) - The calyx lobes are broader, nearly ovate, and soft to the tough. They are about as high as the nutlets. The leaves usually taper to short petioles, or occasionally contracted abruptly and subsessile. The leaf margins are toothed.