| 1 | Inflorescence a simple, unbranched cyme |
| 1' | Inflorescence branched in various ways |
| 2 | All the herbaceous parts covered by stellate, appressed and longer, simple, patent hairs. Inflorescence paniculate |
| 2' | Stellate hairs absent. Inflorescence more or less corymbose, rarely paniculate |
| 3 | Corolla 2-4 cm long. Calyx cylindrical |
| 3' | Corolla shorter than 2 cm. Calyx never cylindrical |
| 4 | Inflorescence paniculate. Leaves more than 3 times as long as wide, lanceolate |
| 4' | Inflorescence more or less corymbose. Leaves ovate, acute, usually less than twice as long as wide |
| 5 | Leaves glabrous to nearly glabrous except along nerves on lower side |
| 5' | Leaves hairy, at least on the whole lower side |
| 6 | Fruit 20-30 mm long. Calyx glabrous, campanulate |
| 6' | Fruit up to 15 mm long. Calyx hairy to glabrescent, cup-shaped |
| 7 | Leaves coriaceous, upper side glabrous, lower side tomentose with hairs brown when dry |
| 7' | Leaves not markedly coriaceous, upper side hairy at least at a younger stage, lower side with hairs of various types |
| 8 | Leaves green on both sides. Hairs reddish brown in all parts. Inflorescence always terminal |
| 8' | Leaves much paler on the lower side. Hairs whitish to greyish, leaving calcareous tubercles on the upper side. Inflorescence terminal or axillary |
