THE GENERAL CHARACTERS OP SEEDS 



409 



Fig. 239. Seeds of Smooth Crab Grass (.pigitaria humifusa). A and B, spike- 

 lets ; A showing the second glume, B' showing the third glume. ' C, D' and E, 

 florets ; D, bearing a portion of the second glume, E, the inner face, showing 

 the edges of the flowering gliime. F, a spikelet of Digitaria fiUformts, show- 

 ing the shorter second glume. G-, the natural size of both of these Species. 

 (After Hillman, Bull. Nevada Agr. Exp. Sta.) 



the third, T-nerved; the fourth, dark purplish brown. Occurrence 

 very frequent in alfalfa clovers and commercial grass seed. 



Crab Grass {Digitwria sanguinalis (L.) Scop.). 



Spikelets one-seventh in. in length with usually persistent scale- 

 like glumes, lanceolate,, pedicellate; second glume usually ciliate 

 on margins, short ; fourth glume silky-villous along marginal nerves, 

 5-nerved, color pale. Frequently occurs in red and alsike clover, 

 as well as in timothy. 



f.O- 



Fig. 240B Figare 2400 



FiQ. 240. Common Crab Grass {Digitaria sanguinalis). 

 of Crab Grass. B, with small glume attached. C. 



A, 

 A, 



an enlarged view 

 spikelets showing 



the second glume, floret, and edges of the third glume. B, the opposite 

 face, showing the minute first glume and third glume. D and B, the two 

 faces of the floret. F, seeds, natural size. 

 (A and B, Drawings by C. M. King; C, after Hillman, Bull. Nevada Agr. 



Exp. Sta.) 



