| 1 | Leaves in whorls of 4-10 |
| 1' | Leaves opposite. |
| 2 | Spicate racemes usually branched and forming a panicle. |
| 2' | Spicate racemes usually simple, terminal, solitary, rarely accompanied by 1 or 2 short spicate racemes at the base. |
| 3 | Habit proportionally slender, verticillasters clearly to even widely spaced, with internodes always visible, less than 1 cm Ø, short appressed-hairy. Calyx 3-3.5 mm (in fr. 3.5-4 mm) long |
| 3' | Habit more robust, axes not slender, verticillasters in an almost continuous thick spike 1-2 cm wide, densely patent-canescent or hirsute. Calyx 4-6 mm (in fr. 5.5-6 mm) long. |
| 4 | Leaves short appressed-hairy to glabrous. Verticillasters grey-pubescent, with dense cincinni of seriate-imbricating, lanceolate, acute bracts, not seldom more or less secund. Calyx tubular, pubescent, without bristles. Spikes several |
| 4' | Leaves with long bristles of c. 1 mm long. Verticillasters very dense, condensed and in few spikes, not secund, not in regularly seriate-imbricating cincinni, the bracts obovate-acute. Calyx somewhat inflated, the teeth not narrow, and shorter in proportion to the tube, the latter with bristle-hairs, but the teeth densely short hairy, at least their margin |
| 5 | Verticillasters distinctly apart. |
| 5' | Verticillasters nearly continuous, occasionally interrupted only at the base; rachis densely tomentose or hairy. |
| 6 | Calyx cylindric, 5-7 mm (in fr. 7-8 mm) long; teeth not spreading. |
| 6' | Calyx campanulate, 4-4.5 mm (in fr. 5-5.5 mm) long; teeth often spreading |
| 7 | Calyx seemingly angled, glabrous except for very scant bristle-hairs on the calyx tube and at the apex of the teeth, and on the bracts. Leaves ovate to broadly ovate, base rounded or cordate |
| 7' | Calyx terete, evenly short pubescent, as are the bracts. Bristle-hairs absent. Leaves oblong-ovate to ovate, base cuneate to rounded |
| 8 | Flowers relatively large; calyx 4.5-5 mm long; corolla 7-8 mm long. Verticillasters 12-20-flowered |
| 8' | Flowers very small; calyx 1.2-1.5 mm long; corolla 2-2.5 mm long. Verticillasters ∞-flowered |
