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216. Phacelurus Grisebach, Spic. Fl. Rumel. 2: 423. 1846.
束尾草属 shu wei cao shu
Authors: Bi-xing Sun & Sylvia M. Phillips
Thyrsia Stapf.
Perennial. Culms often robust. Leaf blades linear or rarely terete; ligule membranous. Inflorescence terminal, racemes usually subdigitate, rarely spread along an elongate axis or solitary. Racemes ± flattened, bearing paired spikelets, horizontally articulated, often rather tardily disarticulating; rachis internodes inflated to clavate, glabrous, base truncate, sometimes with a central peg. Sessile spikelet flat, convex or concave across back; lower glume lanceolate to ovate, membranous to leathery, smooth, marginally 2-keeled or rounded; upper glume boat-shaped; lower floret male or barren, with or without palea; upper floret bisexual, with entire awnless lemma. Pedicelled spikelet resembling sessile but usually smaller and slightly laterally compressed; pedicel free, resembling adjacent rachis internode.
Ten species: Old World tropics, extending northward to SE Europe; three species (one endemic) in China.
Phacelurus resembles Ischaemum in its stout rachis internodes and pedicels and in its male lower floret, and the two genera are probably closely related. Phacelurus differs mainly by the absence of awns.
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| 1 |
Racemes borne on a long central axis; lower glume of sessile spikelet narrowly winged. |
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1 P. zea |
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Racemes subdigitate; lower glume of sessile spikelet wingless |
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(2) |
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| 2 (1) |
Sessile spikelet linear-lanceolate, concave, 8–10 mm; pedicelled spikelet well developed; pedicel cuneate, widened upward; leaves usually glabrous. |
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2 P. latifolius |
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Sessile spikelet ovate-oblong, flat, 6–7 mm; pedicelled spikelet usually reduced; pedicel narrowly oblong, straight; leaves often tuberculate-hispid. |
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3 P. trichophyllus |
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Lower Taxa
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