| 1 | Corolla hairy |
| 1' | Corolla glabrous. |
| 2 | Midrib prominent on the upper surface |
| 2' | Midrib impressed in the upper surface. |
| 3 | Twigs hairy. |
| 3' | Twigs glabrous. |
| 4 | Underside of leaves glabrous. (If leaf margin and petiole beset with closely spaced vesicular glands: 3. S. adenophylla). |
| 4' | Underside of leaves hairy. |
| 5 | Leaves distichous. Bracts caducous |
| 5' | Leaves spirally arranged. |
| 6 | Calyx and ovary glabrous. |
| 6' | Calyx and/or ovary hairy. |
| 7 | Leaves crowded towards the end of the twigs. Twigs thick, tapering towards apex. |
| 7' | Leaves evenly distributed. |
| 8 | Ovary hairy. |
| 8' | Ovary glabrous. |
| 9 | Ovary to c. 1 mm high |
| 9' | Ovary more than 1 mm high. |
| 10 | Leaves distichous. |
| 10' | Leaves spirally arranged. |
| 11 | Inflorescence a fascicle. Bracts persistent. Ovary c. 1 mm high, calyx c. 1 mm long, calyx lobes not becoming longer by tearing. Style base hairy. Fruits ampulliform. |
| 11' | Inflorescence not a fascicle. Bracts caducous. Ovary 1-1½ mm high, calyx 2-3 mm, calyx lobes becoming longer by tearing. Style base glabrous. Fruits not ampulliform. |
| 12 | Calyx and ovary glabrous. |
| 12' | Calyx and/or ovary hairy. |
| 13 | Upper side of leaves hairy |
| 13' | Upper side of leaves glabrous. |
| 14 | Ovary glabrous. |
| 14' | Ovary hairy. |
| 15 | Calyx glabrous. |
| 15' | Calyx hairy. |
| 16 | Bracts to c. 1 mm long. |
| 16' | Bracts longer than 1 mm. |
| 17 | Leaf index more than 3. Leaf margin (and petiole) beset with closely spaced glands. Ovary 1-2 mm high. Stone not ampulliform |
| 17' | Leaf index 2-3. Leaf margin (and petiole) often glandular but glands not closely spaced. Ovary c. 2 mm high. Stone ampulliform |
| 18 | Bracts caducous. Ovary c. 1 mm high. |
| 18' | Bracts persistent. Ovary more than 1 mm high. |
| 19 | Underside of leaves hairy. |
| 19' | Underside of leaves glabrous. |
| 20 | Leaves distichous. Petiole 0-5 mm. Bracts and bracteoles caducous. |
| 20' | Leaves spirally arranged. |
| 21 | Calyx and ovary glabrous. |
| 21' | Calyx and/or ovary hairy. |
| 22 | Ovary to c. 1 mm high. |
| 22' | Ovary more than 1 mm high. |
| 23 | Inflorescence a raceme. Bracts caducous |
| 23' | Inflorescence a (basally branched) spike. Bracts persistent |
| 24 | Twigs thick. |
| 24' | Twigs not thick. |
| 25 | Inflorescence a raceme but pedicels sometimes very short. Bracts caducous. Leaves 15-22 cm long |
| 25' | Inflorescence a raceme but pedicels sometimes very short. Bracts caducous. Leaves 3-6 cm long |
| 25'' | Inflorescence a (basally branched) spike. Bracts persistent. |
| 26 | Disk hairy. |
| 26' | Disk glabrous |
| 27 | Leaves distichous |
| 27' | Leaves spirally arranged. |
| 28 | Ovary glabrous. |
| 28' | Ovary hairy. |
| 29 | Ovary to c. 1 mm high |
| 29' | Ovary more than 1 mm. high. |
| 30 | Calyx glabrous. |
| 30' | Calyx hairy. |
| 31 | Bracts to c. 1 mm long |
| 31' | Bracts longer than 1 mm. |
