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171. Setaria P. Beauvois, Ess. Agrostogr. 51. 1812.
狗尾草属 gou wei cao shu
Authors: Shou-liang Chen & Sylvia M. Phillips
Chaetochloa Scribner, nom. rej.
Annuals or perennials. Culms usually tufted, slender to robust or canelike. Leaf blades linear to lanceolate, sometimes plicate or narrowed to a false petiole; ligule ciliate from a membranous base. Inflorescence a panicle, dense and spikelike or open with the spikelets contracted around the primary branches; spikelets (or some of them) subtended by one to several bristles which persist on the branches after the spikelets fall. Spikelets elliptic, plano-convex, sometimes gibbous, awnless, florets 2; glumes and lower lemma membranous to herbaceous; lower glume ovate from a clasping base, usually less than 1/2 spikelet length, 3–5-veined; upper glume half as long to equaling spikelet, several-veined; lower floret staminate or neuter, sometimes sulcate, its palea present, reduced or absent; upper lemma crustaceous, strongly convex, rugose, punctate or smooth, margins inrolled. x = 9.
About 130 species: tropics and subtropics, extending to warm-temperate regions of the world; 14 species (three endemic, one introduced) in China.
The bristles in the inflorescence represent modified branchlets. The genus includes pasture grasses, a cereal crop, and a few noxious weeds.
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1 |
Panicle open to contracted with obvious, spaced branches; spikelets usually subtended by a solitary bristle (some lacking a bristle, or rarely with up to 3) |
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(2) |
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Panicle densely spikelike with congested branchlets, sometimes lobed; spikelets subtended by several to many bristles |
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(8) |
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2 (1) |
Leaf blades plicate, fusiform-lanceolate to linear-lanceolate, narrowed toward base |
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(3) |
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Leaf blades flat, not plicate, linear or linear-lanceolate, straight or rounded at base |
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(4) |
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3 (2) |
Leaf blades 2–7 cm wide; panicle branches up to 20 cm long; lower glume 1/3–1/2 spikelet length, usually acute to obtuse; lower lemma with narrow falcate apex, longer than upper lemma. |
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1 S. palmifolia |
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Leaf blades 1–3 cm wide; panicle branches up to 8 cm long; lower glume 1/4–1/3 spikelet length, usually broadly obtuse to truncate; lower lemma equaling upper lemma. |
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2 S. plicata |
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4 (2) |
Upper glume subequaling spikelet; only branch or branchlet tips extending into a bristle, rarely a solitary bristle below a few spikelets. |
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3 S. yunnanensis |
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Upper glume distinctly shorter than spikelet; most spikelets subtended by one or more bristles |
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(5) |
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5 (4) |
Tufted annual; upper lemma coarsely rugose. |
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4 S. intermedia |
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Perennials, sometimes rhizomatous; upper lemma smooth or finely punctate-rugose |
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(6) |
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6 (5) |
Plant tufted; bristles stiff, stout; lower floret usually staminate with well-developed palea. |
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5 S. forbesiana |
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Plant with long scaly rhizomes; bristles slender; lower floret neuter with reduced palea |
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(7) |
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7 (6) |
Spikelets elliptic; lower lemma equal to spikelet; upper lemma smooth, shiny. |
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6 S. chondrachne |
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Spikelets lanceolate; lower lemma slightly shorter than spikelet; upper lemma punctate-rugulose. |
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7 S. guizhouensis |
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8 (1) |
Each branchlet from the main axis with only one mature spikelet; upper glume up to 1/2 as long as spikelet, upper floret clearly exposed |
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(9) |
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Each branchlet from the main axis with several mature spikelets; upper glume 2/3 as long to equaling spikelet |
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(10) |
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9 (8) |
Spikelets (2.2–)2.5–3.5 mm; lower floret often staminate, its palea ovate, as wide as upper floret; upper lemma coarsely rugose. |
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8 S. pumila |
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Spikelets 1.8–2.3(–2.5) mm; lower floret neuter, its palea lanceolate, much narrower than upper floret; upper lemma finely rugose. |
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9 S. parviflora |
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10 (8) |
Upper glume 2/3–3/4 length of fertile floret, upper lemma exposed above it; spikelets 2.8–3 mm, acute. |
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10 S. faberi |
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Upper glume subequaling fertile floret, almost completely covering upper lemma; spikelets 2–2.5(–3) mm, usually obtuse |
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(11) |
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11 (10) |
Upper floret falling free from the glumes and lower lemma at maturity; cultivated plant. |
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11 S. italica |
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Upper floret retained within spikelet, this falling whole; wild plants |
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(12) |
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12 (11) |
Bristles retrorsely scabrous. |
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14 S. verticillata |
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Bristles antrorsely scabrous |
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(13) |
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13 (12) |
Spikelets 2–2.5 mm; lower glume 1/4–1/3 as long as the spikelet, usually obtuse. |
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12 S. viridis |
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Spikelets 2.5–3 mm; lower glume ca. 1/2 as long as the spikelet, acuminate. |
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13 S. arenaria |
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List of lower taxa
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