| 1 | Flowering scapes strongly compressed, ancipitous. Leaves abruptly acuminate, shortly caudate, the margins scabrous only at the very top |
| 1' | Flowering scapes terete or trigonous. |
| 2 | Stigmas 4, or in a few flowers 3. Inflorescence consisting of a single spikelet |
| 2' | Stigmas 3, or in a few flowers 4. |
| 3 | Nut lageniform, with a hexagonal, conical, obtuse, densely verruculose beak, 2 mm long. Glumes distinctly spinulose-ciliolate on the upper margin. Inflorescence dense, head-like, or reduced to a single spikelet |
| 3' | Nut with a triquetrous, acute, smooth beak, or beak indistinct. Glumes not or scarcely (not spinulose) ciliolate. |
| 4 | Nut indistinctly beaked, 1½-2½ mm long. Inflorescence usually corymbose, with well-developed rays and many to numerous spikelets |
| 4' | Nut with a distinct, triquetrous, 1¼-3 mm long beak. Inflorescence either consisting of a single spikelet or head-like, with up to 5 spikelets. |
| 5 | Leaves abruptly acuminate, caudate, 8-12 mm wide, their margins scabrous only at the very top, the base narrowed into a 1-5 cm long petiole |
| 5' | Leaves very gradually narrowed into a long point, 4-8 mm wide, scabrous on the margins at least in the upper half, conduplicate at the base, but not distinctly petioled. |
| 6 | Nuts stellately spreading, their upper part dark brown, suddenly narrowed into the pale, obconical lower part. Beak of the nut firm, straight or but slightly curved, hence spikelets echinate. |
| 6' | Nuts obliquely erect, brown, their body ellipsoid, rather gradually attenuate at both ends. Beak of the nut slender, curved; spikelets not echinate |
