1 | Spikelets very small, 2-3 mm long. Glumes 2 mm long. Nut 1½-1¾ mm long. All the leaves usually much reduced, the basal ones bladeless, the cauline ones with a very short blade 1-2(-5) cm long. |
1' | Spikelets, glumes, and nuts larger. At least part of the leaves with well-developed much longer blades. |
2 | Leaves sword-shaped, very flat with sharp edges, equitant. Stems ancipitous. |
2' | Leaves terete, or biconvex with obtuse edges. Stems terete or somewhat compressed, not ancipitous. |
3 | Stems and leaf-sheaths (often also the leaf-blades) asperous. |
3' | Stems and leaves smooth. |
4 | Spikelets in clusters of 3-5. Glumes acute to mucronulate. Nut proper ellipsoid, c. 2 mm long, suddenly contracted into the densely sericeous c. 1½ mm long style-base. |
4' | Most spikelets solitary, some of them in clusters of 2-3. Glumes acutish, muticous. Nut ovoid, gradually passing into the hispid, dark brown to blackish style-base, c. 3 mm long. |
5 | Perianth consisting of (3-)6 bristles c. 2 mm long. Anthers with very shortly produced connective. Inflorescence stiffly erect |
5' | Perianth absent (rarely a single very short bristle present). Anthers with distinctly produced connective. |
6 | Branches of the inflorescence drooping. Filaments strongly elongated after anthesis, (1-)2-2½ cm long, comose |
6' | Branches of the inflorescence erect. Filaments shorter, only moderately elongated after anthesis, never comose. |
7 | Leaves densely ciliate on the edges, narrow, 3-5(-7) mm wide. Stems low, 30-50 cm tall. |
7' | Leaves glabrous, usually broader. Stems usually taller. |
8 | Nut at the base narrowed into a 3-winged stipe, triquetrous. Persistent style-base glabrous or more or less hispid, never densely sericeous |
8' | Nut sessile, obtusely trigonous to subterete. Persistent style-base densely sericeous. |
9 | Lower bracts very shortly laminate. Nut gradually tapering into shortly pyramidal persistent style-base |
9' | Lower bracts long, similar to the leaves. Nut abruptly narrowed into c. 1½ mm long persistent style-base. |
10 | Glumes ovate-lanceolate, acute, the longest c. 5 mm. Spikelets 1-flowered, 5-6 mm long, in turbinate clusters. Nut ovoid-ellipsoid, 3½-4 by 1-1⅓ mm. |
10' | Glumes ovate, obtuse, up to 4 mm long. Spikelets (1-)2-3-flowered, 3-4 mm long, in ovoid to globose clusters. Nut broadly ovoid or subglobose, 3-3½ by 1½ mm. |
11 | Leaves prominently transversely septate. Nut with thickened suberous angles. |
11' | Leaves not septate, pithy within, the pith almost continuous, not divided into remote distinct septa. |
12 | Stem leafless. Spikelets 1-flowered |
12' | Stem with 1-2 short leaves. Spikelets 2-3-flowered. |
13 | Nut ellipsoid to oblong-ellipsoid, 3-5 by 1½-2 mm, smooth and shining. Glumes muticous. |
13' | Nut obovoid or ellipsoid, 1½-2 by 1-1¼ mm, strongly rugulose by many much raised irregular ridges, opaque. Glumes usually mucronulate |