| 1 | Perennials with woody (root-)stock |
| 1' | Annuals with taproots |
| 2 | Leaves canescent-villose; flowers reddish, purplish or pink |
| 2' | Leaves not canescent-villose; flowers white or whitish |
| 3 | Stems sprawling or scrambling with adhesive retrorse bristles; fruits 3-6 mm diam. |
| 3' | Stems erect or diffuse, not markedly adhesive; fruits less than 3 mm diam. |
| 4 | Fruits bristly or scabrid-papillose; leaf-margins retrorsely aculeolate |
| 4' | Fruits smooth or bluntly verruculose; leaf-margins with forward-pointing bristles |
| 5 | Fruits covered with hooked bristles; pedicels divaricate in fruit; corolla lobes c. 1.5 mm long; leaves (4-)6-9(-10)-whorled |
| 5' | Fruits scabrid-papillose; pedicels strongly recurved in fruit; corolla lobes c. 0.8 mm long; leaves 5-6(-8)-whorled |
| 6 | Fruit smooth, 5-6 mm diam. |
| 6' | Fruit conspicuously verruculose, 4-5 mm diam. |
| 7 | Peduncles and pedicels very short, inflorescence as a whole subspicate, with distant verticels of condensed flower-clusters
|
| 7' | Peduncles and pedicels well developed; inflorescences lax, not subspicate |
| 8 | Fruits subglobose |
| 8' | Fruits oblong, distinctly longer than wide |
| 9 | Leaves opposite or 3-4-whorled, ovate or oblong-ovate, obtuse |
| 9' | Leaves (4-)5-10-whorled, setaceous, linear, lanceolate or almost subulate, acute,
mucronate or shortly awned
|
| 10 | Inflorescence arising from the upper nodes of stems and branches, forming
well-marked, terminal, corymbose cymes
|
| 10' | Inflorescences terminal and lateral arising from all but the lowermost nodes and forming ill-defined oblong, pyramidal or obcuneate inflorescence structures |
| 11 | Bracts exceeding or equalling partial inflorescences; fruit distinctly didymous |
| 11' | Bracts shorter than partial inflorescences; fruit inconspicuously didymous |
| 12 | Ultimate branches, peduncles and pedicels not conspicuously slender or capillary; inflorescence relatively strict, ultimate fruits most often 2-3 nodes beyond primary stem axis; fruits hispid (in all the Cyprus material) |
| 12' | Ultimate branches, peduncles and pedicels conspicuously slender and capillary; inflorescence relatively diffuse, ultimate fruits most often 3 or more nodes beyond primary stem axis; fruits glabrous, with blunt papillae but no bristles |
| 13 | Pedicels up to 20 mm long, very elongate and slender; stem generally unbranched except in the inflorescence region |
| 13' | Pedicels usually less than 2-5 mm long; stem usually much branched near the base |
