| 1 | Involucral leaves short (2.5-5 mm long) and mostly spreading so that the immature receptacle becomes or more frequently is always exposed; adult leaves scale-like or equally keeled on four sides, 1-3 mm long. |
| 1' | Involucral leaves curved to surround the young fertile structure (3-13 mm long) and still covering at least the entire immature receptacle before it enlarges when ripe; adult leaves not scale-like nor equally keeled on four sides, 1-6 mm long. |
| 2 | Adult leaves less than 2 mm long, more or less in the form of scales |
| 2' | Adult leaves at least 2 mm long, in the form of short needles |
| 3 | Adult leaves bilaterally flattened. |
| 3' | Adult leaves bifacially flattened. |
| 4 | Involucral leaves surrounding receptacle and mature seed (7-13 mm long); foliage leaves slender (0.6-0.8 mm wide), scarcely keeled |
| 4' | Involucral leaves reaching the base only of the mature seed (5-8 mm long); foliage leaves robust (0.8-1 mm wide), strongly keeled |
| 5 | Involucral leaves less than 5 mm long, not reaching the mature seed; foliage leaves 0.6-1 mm wide. |
| 5' | Involucral leaves 6-10 mm long, mostly covering the mature seed; foliage leaves 0.4-0.6 mm wide |
| 6 | Seed not large (5-6 mm long); foliage leaves spreading |
| 6' | Seed large (7-8 mm long); foliage leaves imbricate |
