| 1 | Corolla tubular, the tube ± twice as long as the calyx, straight or slightly curved. Stamens and style erect, ± straight in anthesis. Leaves in whorls of 3, underneath almost always very laxly hairy on midrib and nerves as is the petiole. Calyx lobes ± equal, corolla lobes ditto. |
| 1' | Corolla tube only for 2-5 mm exceeding the calyx, the limb distinctly zygomorphous, 2 lobes higher connate, patent and longer than the others. Stamens and style patent-curved over this lobe or recurved. Leaves in whorls of 3-4. |
| 2 | Branches of the thyrse triads, or flowers solitary. Pedicels 1¼-2½ cm long. Bud ± cylindric in shape, rarely pear-shaped, often with 5 faint ribs below the lobes. Calyx with a few to several large crateriform glands, the lobes ± equal, in anthesis c. ⅓-¼ as long as the tube. Corolla tube almost cylindric, c. 10 by 5 mm. Stamens c. 3-3½ cm. Leaves in whorls of 3 (by exception 4), hairy underneath or glabrous |
| 2' | Branches of the inflorescence often 2(-3) times forked. Pedicels ½-2 cm. Buds pear- or spindle-shaped, or obovoid, smooth. Calyx without crateriform glands, distinctly widened ± campanulate in anthesis, the lobes mostly unequally tearing, sometimes only 2 or 3, ½-⅔ as long as the tube in anthesis. Corolla tube widened almost from the base, c. 1-1¼ cm high, I½ cm wide at the mouth in anthesis. Stamens 4-4½ cm. Leaves in whorls of (3-)4, always hairy underneath. |
