No. 16. 



SPOROBOLUS ARGUTUS Kth. ( Vilfa Arkansana Trin. Vilfa arguta 



Nees.) 



Plant annual, smooth throughout except the scabrous margins of the leaves. 



Culm tufted, spreading, weak, branching below, smooth, 6 to 12 inches tall. 



Leaves of radical shoots numerous, with mostly smooth, loose, scarious sheaths 

 and flat blades 2 to 3 inches long; of culm 2 or 3, lower sheaths mostly shorter 

 than internodes, close; blades like those of radical shoots, but upper ones much 

 shorter; ligule a line of short tawny bristles. 



Inflorescence a rather narrow or sometimes spreading, erect panicle, 2 to 3 

 inches long, often included at base; branches 3 to 5 at base, alternate above, divided 

 and bearing many pedicellate spikelets on the outer two-thirds. 



Spikelets oblong-ovate, 1-flowered, f line long; first glume oblong, obtusish, 

 thin, hyaline, smooth, 1 -nerved, f line long; floral glume lance-ovate, acute, thin, 

 1-nerved, f line long; palet broadly ovate, thin, obscurely 2-nerved, f line long. 



Grain elliptical, compressed, light-brown, with reddish scar, utricular, falling 

 free. 



PLATE XVI; , empty glumes enlarged; 6, floral glume and palet inclosing 

 grain. 



Texas to Arizona and Mexico. 



