| 1 | Stigma an umbrella-shaped disc on a short style. Plant more or less succulent |
| 1' | Stigma conical or a ring-like structure surpassed by a tubular apical part. Plants not succulent |
| 2 | Leaves broad, ovate to oblong |
| 2' | Leaves narrowly linear to lanceolate. Fruit not ribbed, separating into 4 nutlets |
| 3 | Fruit separating into 2 bilocular pyrenes. Corolla villous inside |
| 3' | Fruit not dividing at all or separating into 4 unilocular nutlets. Corolla not villous inside |
| 4 | Inflorescence corymbose, composed of branched cymes. Fruit separating into 4 nutlets |
| 4' | Inflorescence spike-like, elongate, not corymbose. Fruit remaining undivided. |
| 5 | Apex of carpels profoundly bidentate; carpels 2.5-3 mm long, strongly divergent at last |
| 5' | Apex of carpels entire or slightly bidentate; carpels 4-5 mm long, not or scarcely divergent at last |
| 6 | Inflorescence without bracts. Leaves elliptic to obovate, with silky hairs |
| 6' | Inflorescence with bracts, or flowers in axils of leaves |
| 7 | Stems and branches more or less prostrate |
| 7' | Stems and branches erect or branches more or less divaricate |
| 8 | Flowers single in axils of leaves, crowded apically |
| 8' | Flowers in terminal short, straight cymes, bracts and flowers alternating on each side |
| 9 | Flowers in very dense cymes without any free space between them. Bracts sharply acute, needle-like. Tube of corolla long and slender, strongly inflated by the stamens, surpassing the calyx in length |
| 9' | Flowers not so dense, arranged in 3-8 mm distance of each other. Bracts not so sharply acute, not needle-like. Tube of corolla shorter, usually not or scarcely surpassing the calyx, only weakly inflated by stamens |
| 10 | Style about 1.5 to 2.5 times as long as stigma. Calyx c. 2.5 mm long |
| 10' | Style about as long as stigma. Calyx c. 1.5 mm long |
