1. Cut-leaved Water Horehound, American Water Horehound: Lycopus americanus - 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.

2. Western Water-horehound, Rough Bugleweed, Rough Water-horeound: Lycopus asper - 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.

3. Northern Bugle-weed: Lycopus uniflorus - 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.