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165. Brachiaria (Trinius) Grisebach, Ledebour, Fl. Ross. 4: 469. 1853.
臂形草属 bi xing cao shu
Authors: Shou-liang Chen & Sylvia M. Phillips
Panicum sect. Brachiaria Trinius, Gram. Panic. 51, 125. 1826.
Annual or perennial. Leaf blades linear to lanceolate, often with cartilaginous margins. Inflorescence composed of racemes along a central axis; raceme rachis triquetrous or flattened, sometimes winged; spikelets sessile or pedicelled, single or paired, rarely in fascicles or on secondary racemelets. Spikelets plump, usually elliptic, florets 2; lower glume adaxial, varying in length from very small and veinless to many-veined and subequaling spikelet, base sheathing, sometimes extended downward as a short stipe; upper glume and lower lemma similar, as long as spikelet, membranous or cartilaginous; upper lemma coriaceous, smooth, striate or rugose, margins inrolled, apex obtuse to acute, occasionally minutely mucronate; upper palea apex tucked within lemma. x = 7, 9.
About 100 species: tropics and subtropics mainly of the Old World, especially Africa; nine species (one endemic) in China.
Brachiaria is sometimes included within Urochloa, but usually they can be distinguished without difficulty.
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| 1 |
Culms robust, up to 2 m tall; inflorescence with 10–20 racemes. |
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1 B. mutica |
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Culms slender, up to 60 cm tall; inflorescence with less than 10 racemes |
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(2) |
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| 2 (1) |
Inflorescence with erect appressed racemes; fertile floret smooth and shiny, obtuse, readily falling from spikelet. |
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2 B. eruciformis |
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Inflorescence with spreading racemes; fertile floret rugulose, acute to mucronate, persistent within the spikelet |
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(3) |
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| 3 (2) |
Spikelets 1.5–2.7 mm; leaf blades broadly lanceolate, 1–4 cm long |
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(4) |
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Spikelets 2.5–4 mm; leaf blades lanceolate or linear-lanceolate, 4–15 cm long |
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(5) |
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| 4 (3) |
Spikelets elliptic, 2–2.7 mm. |
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3 B. villosa |
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Spikelets ovate, gibbous, 1.5–2 mm. |
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4 B. semiundulata |
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| 5 (3) |
Spikelets paired, one subsessile and one pedicelled. |
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5 B. ramosa |
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Spikelets single (except sometimes at raceme base) |
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(6) |
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| 6 (5) |
Rachis of racemes triquetrous, 0.2–0.4 mm wide; spikelets herbaceous, pubescent or glabrous |
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(7) |
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Rachis of racemes flat on back, 0.4–0.5 mm wide; spikelets cartilaginous, glabrous or almost so |
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(8) |
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| 7 (6) |
Spikelets contiguous, 3.8–4 mm, pubescent. |
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6 B. fusiformis |
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Spikelets distant, 2.5–3.5 mm, glabrous. |
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7 B. kurzii |
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| 8 (6) |
Lower glume 1/3–1/2 spikelet length, separated from upper glume by a short internode; upper lemma subacute. |
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8 B. subquadripara |
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Lower glume 1/2–3/5 spikelet length, not separated from upper glume; upper lemma mucronate. |
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9 B. urochlooides |
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List of lower taxa
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