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163. Echinochloa P. Beauvois, Ess. Agrostogr. 53. 1812.
稗属 bai shu
Authors: Shou-liang Chen & Sylvia M. Phillips
Tema Adanson, nom. rej.
Annual or perennial. Culms often coarse and robust. Leaf blades flat, linear or broadly linear; ligule absent (ciliate in some species outside China). Inflorescence composed of racemes along a central axis; racemes simple or compound, densely spiculate, spikelets paired in 4 rows, or congested on secondary racemelets. Spikelets narrowly elliptic to subrotund, plump, plano-convex, often hispidulous or spinulose, acute to awned; lower glume triangular, 1/3–1/2(–3/5) spikelet length, sheathing; upper glume and lower lemma equaling the spikelet or upper glume somewhat shorter in cultivated forms, prominently 5–7-veined, acute to rostrate or lower lemma extended into a stout awn; upper lemma coriaceous, smooth, shining, terminating in a short, laterally compressed, incurving beak; upper palea acute, apex briefly reflexed. x = 9.
About 35 species: tropical and warm-temperate regions of the world; eight species (at least one introduced) in China.
The reflexed upper palea tip, although a very tiny character, is nevertheless important for distinguishing Echinochloa from neighboring genera, especially Brachiaria. The absence of a ligule is also a good spot character for recognition of the genus in China. Species of Echinochloa typically grow in aquatic or moist situations. Several have become widespread weeds, especially of irrigated crops, and two are sometimes cultivated as minor cereals.
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| 1 |
Grain persisting at maturity; spikelets plumply ovate; branches of inflorescence incurving; cultivated plants |
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(2) |
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Grain readily deciduous at maturity; spikelets ovate, ovate-lanceolate or ovate-elliptic; branches of inflorescence not incurving; wild plants |
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(3) |
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| 2 (1) |
Spikelets dark greenish when mature, awnless; racemes rather spaced, simple. |
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1 E. frumentacea |
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Spikelets purplish brown when mature, acute to awned, awn 0.5–2 cm; racemes very dense, closely packed, usually branched |
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2 E. esculenta |
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| 3 (1) |
Lower lemma convex, hard and shining. |
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6 E. glabrescens |
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Lower lemma flat on the back, herbaceous |
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(4) |
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| 4 (3) |
Spikelets ovate, 3.8–6 mm; culms erect, forming narrow tuft. |
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3 E. oryzoides |
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Spikelets elliptic-ovate, mostly 2–4 mm; culms spreading, forming loose tuft |
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(5) |
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| 5 (4) |
Racemes neatly 4-rowed, simple, openly spaced, often erect; spikelets awnless, acute, 2–3 mm. |
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4 E. colona |
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Racemes untidily 2- to several-rowed, at least the longer often with short branchlets; spikelets acuminate to shortly awned, 2–4 mm |
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(6) |
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| 6 (5) |
Racemes distinctly compound with many short branchlets; spikelets 2–3 mm; awn of lower lemma 1–1.5 cm. |
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5 E. cruspavonis |
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Racemes simple or only inconspicuously branched; spikelets 2.5–4 mm; lower lemma acute to long-awned |
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(7) |
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| 7 (6) |
Inflorescence green or purple-tinged, moderately dense; spikelets 3–4 mm; lower lemma acuminate or awned |
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7 E. crusgalli |
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Inflorescence dark purple, very dense; spikelets 2.5–3 mm; lower lemma awned, awn 3–5 cm. |
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8 E. caudata |
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List of lower taxa
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