1Flowering scapes strongly compressed, ancipitous. Leaves abruptly acuminate, shortly caudate, the margins scabrous only at the very top
1'Flowering scapes terete or trigonous.
2Stigmas 4, or in a few flowers 3. Inflorescence consisting of a single spikelet
2'Stigmas 3, or in a few flowers 4.
3Nut 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.
4Nut 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.
5Leaves 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.
6Nuts 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