Northern Prairie Wildlife Research Center
| Lead | Characteristic | Go To |
| 1 | Corolla regular or nearly so, the lobes subequal. | Lead 2 |
| 1 | Corolla distinctly irregular, the lobes unequal. | Lead 3 |
| 2 | Stamens 2; plants not strongly aromatic. | Genus Lycopus |
| 2 | Stamens 4; plants strongly mint-scented. | Genus Mentha |
| 3 | Upper lip of the corolla lacking, the lower lip prominent, the other 4 corolla lobes positioned on its lateral margins. | Genus Teucrium |
| 3 | Both upper and lower lips of the corolla well-developed. | Lead 4 |
| 4 | Calyx with a rounded protuberance on the upper side, 2-lipped, not toothed. | Genus Scutellaria |
| 4 | Calyx without a dorsal protuberance, toothed, 2-lipped or not. | Lead 5 |
| 5 | Flowers short-pedicelled, borne singly in the axils of short bracts, the inflorescence comprised of 1-several, terminal and lateral racemes. | Genus Physostegia |
| 5 | Flowers sessile and whorled, in a continuous or interrupted terminal spike. | Lead 6 |
| 6 | Calyx strongly 2-lipped, unequally 5-toothed; spike dense, continous. | Genus Prunella |
| 6 | Calyx not strongly 2-lipped, with 5 equal or subequal teeth; spike interrupted. | Genus Stachys |