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|1 Beaks of perigynia glabrous or with scattered spreading hairs on main veins; leaf blades finely papillose on the lower surface (and also usually long-pubescent); vegetative culms hollow, spongy (flattened when pressed)|
|1 Beaks of perigynia pubescent or scabrous both on and between main veins; leaf blades glabrous or pubescent abaxially, but not papillose; vegetative culms hard.|
|..2 Leaf blades pubescent; [rare introduction]|
|..2 Leaf blades glabrous; [native].|
....3 Perigynia glabrous or scabrous on main veins, 4.8-8.4 mm long
|....3 Perigynia pubescent, 6-11.5 mm long|