| 1 | Placentation marginal or parietal, thus the capsule valves carrying placentae and seed with them on dehiscence. |
| 1' | Placentation axile, free-central or basal, valves eseptate or with septum, in any case pulling away from placentae on dehiscence. |
| 2 | Bracts with evident dorsal area but not keeled; keel of lateral sepals lacerate or lacero-fimbriate at least toward tip; capsule valves thin. |
| 2' | Bracts lacking evident dorsal area but upwards keeled; keel of lateral seoals entire; capsule valves indurate. |
| 3 | capes multicostate distally; dorsal area of bracts with a strong midvein with evident branches; seeds at least 1 mm long. |
| 3' | Scapes usually either 2-edged or with but 2 strong ribs distally; dorsal area of spike bracts lacking a strong midvein, this if evident unbranched; seeds no longer than 0.9 mm. |
| 4 | Ribs or edges of scape smooth; seeds ellipsoid-fusiform, usuallv farinose. 0.7-0.9 mm; plant base suffused with red or purple. |
| 4' | Ribs or edges of scape papillose or papillose-tuberculate; seeds broadlv ellio- soid, translucent, 0.4-0.5 mm; plant base not reddened. |
| 5 | Leaf sheaths with at least some cilia. |
| 5' | Leaf sheaths with glabrous margins. |
| 6 | Capsule valves with an attached septum; spikes dark-brown; leaf blades papillose or finely rugulose-papillose. |
| 6' | Capsule valves lacking an attached septum; spikes lighter-colored; leaf blade surfaces various. |
| 7 | Scapes distally Battened, the sharp edges continuously or interruptedly cilate-scabrid to pilose; leaf blade tips asymmetric and rounded. |
| 7' | Scapes terete, smooth, lustrous, punctate; leaf blades abruptly narrowed to an excentric spine or spinule. |
| 8 | Scapes 2-3 mm wide, their edges pilose-ciliate; spike bracts with large and distinct dorsal area. |
| 8' | Scapes ca. 1 mm wide, their edges scabro-ciliate or ciliolate; spike bracts lacking dorsal area. |
| 9 | Spike bract margins scarious, broad, lacerate, of distinctly and abruptly different color and texture; dorsal area lacking. |
| 9' | Spike bract margins, if thin and lacerate neither broad nor abruptly contrasting in texture or color; dorsal area evident on at least some bracts. |
| 10 | Bract margins reddish; seeds ca. 1 mm long. |
| 10' | Bract margins pale; seeds 0.5-0.7 mm long. |
| 11 | Spikes ovoid to cylindric, mostly over 1.5 cm long; leaf and scape surfaces with golden tints, edges of both golden-ciliate; lateral sepals free |
| 11' | Spikes broadly ellipsoid to obovoid or globose, ca. 1 cm long; lear and scape surfaces without yellow tints, the edges of both smooth or ciliolate; lateral sepals, or some of them, connate. |
| 12 | Leaf sheath bases bright to dull brown, eciliate to sparsely ciliate; apices of fertile bracts broadly rounded, the lacerate-scarious borders distinctly red; edges of leaf blades entire or inconspicuously ciliolate. |
| 12' | Leaf sheath bases lustrous deep brown or pale brown, mostly evidently cilio- late; apices of fertile bracts narrowed, somewhat keeled, the scarious bor- ders pale or pale red-brown; edges of leaf blades denselv ciliolate with fine. white hairs. |
| 13 | Larger bracts acute to acuminate,toward apex; leaf sheath base strongly orbicu- lar-dilated, usually with broad, dark brown or castaneous borders; plants rarely to 20 cm tall, stems often elongated (sometimes to lO cm) with frond-like plates of leaves; high elevations. |
| 13' | Larger bracts rounded toward apex; leaf sheath base less dilated, borders paler, less contrasting; plants rarely as short as 20 cm, stems mostly contracted (rarely to 2 cm), not producing frond-like plates of leaves; medium to high elevations. |
| 14 | Spikes ovoid, broadly ellipsoid or subglobose, flowering bracts broadly obovate to suborbicular; scapes linear, upwards with 3 or more narrow but strong ribs; plants sub-bulbous, leaves erec. |
| 14' | Spikes lanceoloid to ellipsoid, flowering bracts narrowly ovate; scapes muorm, upwards with l-3 ribs; lateral sepals lanceolate; plants non-bulbous, leaves flabellately spreading or erect. |
| 15 | Scape ribs 0-2, smooth or papillose; plants over 20 cm high, the leaves ascending to erect, with ciliolate blades. |
| 15' | Scape ribs mostly 1-3, smooth to scabrid; plants mostlv lower. the leaves in fans, the blades entire to ciliate. |
| 16 | Leaf blades filiform, terete or oval, sulcate ventrally above a strong pale ligule; sheath base elongate, castaneous; bracts with broad, white-villose borders. |
| 16' | Leaf blades or sheaths or bracts not as above. |
| 17 | Plants robust with firm, hard, mostly uniformly deep brown to castaneous or sooty sheaths, in sharp color contrast to blades; stems mostly evident, deve- loping fans of closely imbricate leaves; seeds over 1 mm; capsule valves with septum at least toward valve base; dorsal area lacking or indistinct. |
| 17' | Plants of various habit but with leaf sheath base either softer and paler or dark only at very base; stems not elongate; seeds 1 mm long or less; capsule valves eseptate; dorsal area evident or lacking. |
| 18 | Sea pes strongly flattened, margins densely ciliolate or ciliate; leaf blades densely ciliate. |
| 18' | Scapes not flattened, rounder and more slender, the ribs smooth. rarelv ciliate: leaf blades smooth or papillose, rarely ciliolate. |
| 19 | Spikes mostly paired at scape tip. |
| 19' | Spikes solitary. |
| 20 | Scape and leaves rusty-ciliate; spikes globose to obovoid, bracts dull; seeds less than 2 mm; plants mostly 15-40 cm high. |
| 20' | Scape and leaves pale-ciliate; spikes subglobose, rarely ovoid, bracts lustrous: seeds over 2 mm; plants 40-100 cm high. |
| 21 | Dorsal area of bracts not evident; bracts with broad scarious lacerate borders distinctly different in texture and color. (see couplets 11-12) |
| 21' | Dorsal area evident on some or all bracts; bracts not bordered as above. |
| 22 | Dorsal area of 1-several outer bracts produced as a strong mucro, cusp or blade. |
| 22' | Dorsal area of outer bracts not produced as above (plants mostly low, with wiry or filiform, distally subterete scapes, annual or short-lived perennial). |
| 23 | Scapes distally terete, there usually with 1 low rib; dorsal area of lower 1-2 bracts excurrent as a strong mucro or blade-like cusp; lateral sepals to 1/3 connate. the tips reddish-villous; slender plants with glaucous foliage |
| 23' | Scapes flattened, the 2 edges winged; dorsal area variously excurrent; lateral sepals free or connate, the tips not red-villous; foliage not glaucous. |
| 24 | Empty outer bracts several, spreading to form a broad, leafy involucre: scaoe margins ciliate; plants mostly 30-50 cm tall. |
| 24' | Empty outer bracts few, incurved, often with a short-excurrent dorsal area; scape margins eciliate or papillose; annuals 6-22 cm tall. |
| 25 | Lateral sepals free; flowers few to many. |
| 25' | Lateral sepals connate; flowers 1-2(-4). |
| 26 | Lateral sepals subequilateral, slightly curved, keel papillose to smooth, rarely ciliolate. |
| 26' | Lateral sepals strongly inequilateral, very curved, keel ciliolate or ciliate. |
| 27 | Leaf blade strongly flattened, its margin a narrow, pale, incrassate band. |
| 27' | Leaf blade not strongly flattened, its margin not as above. |
| 28 | Ligule 2-3 mm long; leaves soft, the erect ones much exceeded by scapes, the blade surfaces ribless or inconspicuously ribbed; lateral sepal tips blunt; plants aquatic or emergent in frequently inundated savanna. |
| 28' | Ligule no longer than 1.5 mm; leaves firm, erect, (nearly) as long as sea pes, the blade surfaces strongly ribbed; lateral sepal tips sharp; plants of higher or drier sites. |
| 29 | Staminodes, if present, beardless; seeds with truncate and minutelv aniculate apex; foliage and scapes usually papillose-rugulose. |
| 29' | Staminodes present and bearded; seeds with acuminate apex; foliage and scapes smooth, though blade margins sometimes ciliate. |
| 30 | Dorsal area of bracts epapillose; keel of leaf sheath and sometimes 1 or both blade margins wiry, lustrous, deep brown, sometimes irregularly ciliate; bract margins glabrous. |
| 30' | Dorsal area of bracts papillose-tuberculate; keel of leaf sheath and blade margins neither wiry-bordered nor ciliate; bract margins often villosulous near apex. |
| 31 | Lateral sepals as viewed from the side broadly oblong and blunt; spikes predominantly ovoid to nearly round, mostly 5 mm long or less. |
| 31' | Lateral sepals as viewed from the side lanceolate and acute; spikes ellipsoid to cylindric, at maturity predominantly 1-2 cm long. |
| 32 | Leaf blades flat, filiform, 0.3-0.5 mm wide; spike 1-flowered. |
| 32' | Leaf blades linear, 0.8-1.2 mm wide; spike mostly 2-flowered |
