| 1 | Leaves serrate to irregularly dentate. Inflorescence paniculoid or thyrsoid |
| 1' | Leaves entire or with few irregular teeth. Inflorescence corymbose or with few cymose branches |
| 2 | Cymes few-flowered, always axillary, bracteate; lower bracts up to 10 mm long |
| 2' | Inflorescence terminal or axillary, with branched or unbranched cymes or corym- bose, without or with few bracts at base of branches |
| 3 | Tube of corolla 3.5-5 times as long as the calyx; lobes one third, rarely up to half as long as tube, recurved. Fruit up to 10 mm long |
| 3' | Tube of the corolla shorter compared to the calyx and lobes. Fruit 8 mm long or shorter |
| 4 | Anthers sagittate, with a narrow but distinct sinus between their lower ends. Often also veins of higher order distinct, forming a dense network |
| 4' | Anthers not sagittate, linear, sometimes widened and rounded at base. Only pri- mary nerves prominent |
| 5 | Inflorescence branched, with 1-5 flowers all on one side of each branch, on short pedicels (0.5-1 mm) |
| 5' | Inflorescence branched, flowers single (rarely 2 or 3) terminal on branches of ulti- mate order, not all on one side of main branches |
| 6 | Inflorescence glabrous |
| 6' | Inflorescence shortly pubescent, sometimes with glands |
| 7 | Leaves ovate to lanceolate, with distant primary nerves usually 1 cm or more apart at their base |
| 7' | Leaves obovate to oblanceolate, sometimes emarginate at apex, with very dense primary nerves less than 1 cm apart at their base |
| 8 | Inflorescence glabrous or nearly glabrous |
| 8' | Inflorescence hairy |
| 9 | Leaves acute or acuminate. Calyx 1.2-1.5 mm long, cleft to middle or a little beyond, lobes glabrous or with few hairs along margin. Style cleft for about 0.8 mm |
| 9' | Leaves rarely acute, usually obtuse or emarginate. Calyx 2.5 mm long, cleft for about 2 mm, lobes densely ciliate along margin. Style cleft for most of its length |
| 10 | Scandent shrubs. Calyx densely covered with very short reddish, strigillose hairs. Young branches with loose patent bristles sometimes thorn-like with broader base |
| 10' | Trees. Calyx without reddish hairs, sometimes ciliate along margin and/or cover- ed with white pustules. Young branches glabrous |
| 11 | Corolla-tube distinctly longer than calyx. Calyx lobes with patent, long hairs along margin, glabrous on surface |
| 11' | Corolla-tube included in calyx. Calyx lobes ciliate along margin, white pustulate on surface |
