| 1 |
Bisexual spikelets dominant on inflorescences; disk subtending nutlet either stipelike or indistinct |
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(2) |
| + |
Bisexual spikelets few or absent on inflorescences; disk subtending nutlet lobed or cup-shaped (but not well developed in S. novae-hollandiae) |
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(6) |
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| 2 (1) |
Annuals, without a rhizome; inflorescences spicate; glumes ovate; nutlet surface transversely rugose. |
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1 S. pergracilis |
| + |
Perennials, with a woody creeping rhizome; inflorescences paniculate; glumes lanceolate or ovate-lanceolate; nutlet surface smooth, subsmooth, or slightly rugose |
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(3) |
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| 3 (2) |
Spikelets 4-10 mm, pilose; disk stalklike |
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(4) |
| + |
Spikelets 3-4.5 mm, glabrous; disk appressed to nutlet |
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(5) |
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| 4 (3) |
Nutlet 1.5-1.8 mm, covered with tufts of stellate hairs; contraligule absent. |
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2 S. neesii |
| + |
Nutlet 2.5-2.7 mm, glabrous; contraligule narrow. |
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3 S. tonkinensis |
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| 5 (3) |
Culms 30-60 cm tall, 1.4-2 mm thick; leaf blade 1.5-2 mm wide; lateral branches of inflorescence often spicate, single; nutlet ca. 2.5 mm. |
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4 S. lithosperma |
| + |
Culms 60-200 cm tall, 3-7 mm thick; leaf blade 15-20 mm wide; lateral branches of inflorescence cymose, often binate; nutlet ca. 3.5 mm. |
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5 S. corymbosa |
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| 6 (1) |
Small annuals (or short-lived perennials); rhizomes absent or not well developed |
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(7) |
| + |
Perennials; rhizomes well developed and prominent |
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(11) |
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| 7 (6) |
Involucral bracts linear-lanceolate; nutlet ca. 1.5 mm in diam.; disk lobes obtuse. |
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7 S. rugosa |
| + |
Involucral bracts setaceous; nutlet ca. 2 mm in diam.; disk lobes acute or acuminate |
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(8) |
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| 8 (7) |
Leaf sheath glabrous; disk ca. 1/2 height of nutlet, lobes brown, membranous, apex acuminate; nutlet surface smooth |
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(9) |
| + |
Leaf sheath villous; disk 1/4-1/3 height of nutlet, lobes yellowish white, thick, apex acute; nutlet surface pitted with regular longitudinally elongate pattern |
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(10) |
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| 9 (8) |
Nutlet ± spherical, apex with purple tip. |
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8 S. biflora |
| + |
Nutlet trisulcate, apex with yellowish white tip. |
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9 S. laxa |
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| 10 (8) |
Nutlet 2-2.5 mm, subovoid-spherical; perianth lobes rounded at apex. |
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6 S. novae-hollandiae |
| + |
Nutlet 2.8-3 mm, spheroid to obovoid-spherical; perianth lobes acute at apex. |
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10 S. parvula |
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| 11 (6) |
Culms terete or slightly 3-angled; leaf sheath not winged |
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(12) |
| + |
Culms 3-angled or triquetrous; leaf sheath winged at middle part of culm (not obviously in S. hookeriana) |
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(13) |
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| 12 (11) |
Nutlet surface smooth, only apically slightly hispid; disk not cup-shaped, scarcely 1/5 height of nutlet, appressed to base of nutlet, lobes triangular, margins reflexed; leaves alternate, well spaced, not whorled. |
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23 S. harlandii |
| + |
Nutlet surface hexagonally reticulate, pilose; disk cup-shaped, 1/2-4/5 height of nutlet and enclosing it, lobe apex dentate, margins not reflexed; leaves ± 3-whorled. |
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24 S. sumatrensis |
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| 13 (11) |
Nutlet smooth |
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(14) |
| + |
Nutlet ± reticulate and stellate-hairy |
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(17) |
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| 14 (13) |
Inflorescences subspicate, branches short or without secondary branches; spikelets with 3-5 awns; nutlet 4-4.5 mm; disk obscurely 3-lobed. |
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19 S. psilorrhiza |
| + |
Inflorescences paniculate; spikelets without or with fewer fine awns; nutlet 3-3.5 mm; disk obviously 3-lobed |
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(15) |
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| 15 (14) |
Bractlets glumelike, shorter than spikelet; leaf blade thickly leathery, contraligule scarcely developed; stamen 1; nutlet ca. 2.5 mm in diam.; disk lobes triangular. |
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20 S. poiformis |
| + |
Bractlets setaceous, longer than spikelet; leaf blade papery, contraligule conspicuous and triangular; stamens 3; nutlet ca. 2 mm in diam.; disk lobes subrounded at apex |
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(16) |
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| 16 (15) |
Inflorescences with 4 or 5 lateral branches; disk lobes semicircular. |
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21 S. radula |
| + |
Inflorescences with 1-3 lateral branches; disk lobes ovate. |
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22 S. oblata |
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| 17 (13) |
Glumes blackish purple; leaf sheath obscurely winged; inflorescences without or rarely with a distant branch. |
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11 S. hookeriana |
| + |
Glumes brown or reddish brown; leaf sheath obviously winged; inflorescences with 1-3 distant branches |
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(18) |
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| 18 (17) |
Contraligule oblong to oblong-lanceolate, 4-12 mm, glabrous. |
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12 S. ciliaris |
| + |
Contraligule depressed rounded, semicircular or nearly semicircular, at most 4 mm, ciliate or glabrescent |
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(19) |
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| 19 (18) |
Disk slightly 3-lobed or barely lobed; lobes flatly semicircular, apex rounded |
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(20) |
| + |
Disk deeply 3-lobed; lobes lanceolate-triangular or ovate-triangular, apex acute to subtruncate |
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(21) |
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| 20 (19) |
Nutlet with white reticulation. |
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13 S. terrestris |
| + |
Nutlet with purplish brown reticulation. |
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14 S. dulungensis |
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| 21 (19) |
Nutlet ca. 2 mm in diam., rugose. |
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15 S. levis |
| + |
Nutlet 2.5-2.8 mm in diam., reticulate-pitted or scrobiculate |
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(22) |
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| 22 (21) |
Leaves alternate, not whorled; disk yellowish white. |
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16 S. jiangchengensis |
| + |
Leaves in whorls of 2-5; disk brownish purple |
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(23) |
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| 23 (22) |
Nutlet whitish when mature, 2.2-2.7 mm wide, scrobiculate to smooth. |
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17 S. scrobiculata |
| + |
Nutlet at first whitish but brownish purple when mature, 1.7-2 mm wide, cancellate. |
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18 S. purpurascens |
