156 GRASSES OF BRITAIN. 



Setaria Viridis. 



Erect Bristle-Grass. 



Plate LXVIII. 



Specific Character. — Involucral bristles with erect teeth. 



Description. — Root annual, fibrous, producing stems from three to 

 eighteen inches in length. Stems erect, hollow, mostly branched be- 

 low, rough above, bearing four or five leaves with smooth striated 

 sheaths, the upper sheath shorter than its leaf. Ligule of upper 

 sheath short, blunt, fringed, the length about equal to one-third of 

 the breadth. Joints usually four, the upper situated rather below 

 the centre of the stem, and frequently covered by the second sheath. 

 Leaves flat, lanceolate, rough, especially on the margins. Inflores- 

 cence simple panicled, the branches very short, the rachis hairy. 

 Spikelets dorsally compressed, crowded on all sides, nearly sessile, 

 arranged in clusters, furnished at the base with long, rough, involu- 

 cral bristles more than twice the length of the spikelet ; each bristle 

 strongly toothed, the teeth pointing upwards. Each spikelet composed 

 of two glumes and two florets, and although usually green has occa- 

 sionally a purple tinge. Glumes two, very unequal, the lowermost 

 considerably the smaller, broad and pointed, the upper glume of an 

 oblong form, smooth, five-ribbed. Lowermost floret barren, of one 

 palea, very similar in size and appearance to the larger glume, and 

 by some authors has been considered as a third glume. Upper flo- 

 ret of two palese, the outer the larger, concave, three-ribbed, the sur- 

 face minutely dotted in longitudinal lines ; the inner palea flattish, 

 folded, and also minutely dotted. Sti/les two, distinct, long, and 

 smooth, arising fi-om the summit of the ovarium. Stigmas short and 

 feathery. Stamens three. Anthers dark purple. Seeds hard and 

 pohshed. 



Obs. — Setaria viridis is easily distinguished from Setaria verticil- 

 lata^ in the involucral bristles being about three times the length of 

 the spikelet, and furnished with minute teeth directed upwards, (see 

 Y\g. 2) ; — while in Setaria verticillata the involucral bristles are not 



Setaria firidts, Beauv., Koch, Hooker, Lind., Bab., Kunth. Panicum Hride, Linn., 

 Smith, Knapp, Schrad., Leers. 



