American Water-horehound, American Water Horehound, Cutleaf Water-horehound, Cutleaf Water Horehound, Cut-leaved Water Horehound: Lycopus americanus (Synonyms: Lycopus americanus var. longii, Lycopus americanus var. scabrifolius, Lycopus sinuatus) - Calyx lobes firm, narrower, noticeably longer than the mature nutlets. Leaves taper to a short petiole. Blades with large, irregularly toothed or subpinnatifid margins.
Pacific Water Horehound, Rough Bugleweed, Rough Water-horehound: Lycopus asper (Synonyms: Lycopus lucidus, Lycopus lucidus ssp. americanus, Lycopus lucidus var. americanus) - Calyx lobes firm, narrower and noticeably longer than the mature nutlets. Leaves more or less sessile with abruptly narrowing base or occasionally more tapered at the base. Blade margins evenly and coarsely toothed.
Northern Bugleweed: Lycopus uniflorus (Synonyms: Lycopus uniflorus var. uniflorus, Lycopus virginicus var. pauciflorus) - Calyx lobes soft, wider, shorter, barely longer than the mature nutlets. Leaves generally tapering to a short petiole, but occaskionally subsessile and more abruptly tapering. Leaf margins toothed