Key for Xyris Linnaeus

1Placentation 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.
2Bracts 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.
3capes 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.
4Ribs 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.
5Leaf sheaths with at least some cilia.
5'Leaf sheaths with glabrous margins.
6Capsule 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.
7Scapes 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.
8Scapes 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.
9Spike 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.
10Bract margins reddish; seeds ca. 1 mm long.
10'Bract margins pale; seeds 0.5-0.7 mm long.
11Spikes 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.
12Leaf 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.
13Larger 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.
14Spikes 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.
15Scape 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.
16Leaf 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.
17Plants 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.
18Sea 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.
19Spikes mostly paired at scape tip.
19'Spikes solitary.
20Scape 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.
21Dorsal 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.
22Dorsal 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).
23Scapes 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.
24Empty 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.
25Lateral sepals free; flowers few to many.
25'Lateral sepals connate; flowers 1-2(-4).
26Lateral sepals subequilateral, slightly curved, keel papillose to smooth, rarely ciliolate.
26'Lateral sepals strongly inequilateral, very curved, keel ciliolate or ciliate.
27Leaf blade strongly flattened, its margin a narrow, pale, incrassate band.
27'Leaf blade not strongly flattened, its margin not as above.
28Ligule 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.
29Staminodes, 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.
30Dorsal 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.
31Lateral 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.
32Leaf 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