| 1 | Leaves mostly radical and pinnate or 1-2-pinnatifid (3 or 5 leaflets). Rhizomatous herb, usually less than 20 cm high. Style-branches nearly equal |
| 1' | Leaves cauline, entire or serrate, but not pinnatifid. Erect or procumbent herbs, usually more than 30 cm high. Style-branches very unequal. |
| 2 | Calyx fully covered with viscid, glandular hairs, less than 7 mm long in the fruiting stage. Flowers blue. |
| 2' | Calyx covered with hispid, strigose or curly hairs, not viscid-glandular, more than 8 mm long in the fruiting stage. |
| 3 | Stem alternately with 2 rows of hairs on the nodes in the middle of the sides. Calyx in fruit c. 3-4 mm. Upper lip broad, acute |
| 3' | All four sides of the stem hairy. |
| 4 | Spurious racemes rather dense (nodes c. 0.5 cm), in fairly short panicles. Plant c. 40-70 cm. Calyx in fruit c. 3-4 mm, the lips and teeth acute |
| 4' | Spurious racemes rather lax (nodes c. 1 cm), slender. Plant c. 0.5-1.5 m. Calyx in fruit 5.5-7 mm, upper lip short-mucronate, the two teeth of the underlip clearly mucronate. |
| 5 | Verticillasters distant, internodes 1-2 cm. Corolla 12-17 mm longer than the calyx. Flowers red |
| 5' | Verticillasters approximate, internodes 2-5 mm. Corolla 2-3 mm longer than the calyx. Flowers purplish blue |
