| 1 | Flowers in terminal leafless racemes or panicles |
| 1' | Flowers or verticillasters axillary, or plant never flowering. |
| 2 | Leaves all or for the greater part with a rounded to truncate or shallow-cordate, rarely broadly cuneate base. Stem quadrangular, not grooved, very thinly short-hairy or glabrous. |
| 2' | Leaves with an acute to obtuse, cuneate, usually not very broad base. Stem more hairy than in the preceding species. |
| 3 | Verticillasters globose, dense. Calyx rather densely long-hairy, 10-nerved, c. 3 mm long, throat after anthesis closed by a ring of hairs |
| 3' | Verticillasters not globose, rather dense. Calyx densely short-hairy, with 5 thick nerves and some thinner ones, c. 2 mm long, glabrous inside |
