THE GENERAL CHARACTERS OF SEEDS 



409 







Fig. 239. Seeds of Smooth Crab Grass (Digitaria 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 glume. F, a spikelet of Digitaria filiformiSj show- 

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

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



the third, 7-nerved; the fourth, dark purplish brown. Occurrence 

 very frequent in alfalfa clovers and commercial grass seed. 



Crab Grass (Digitaria 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. 



*.*• 



Fig. 240B Figure 240C 



Fig. 240. Common Crab Grass (Digitaria sanguinalis). A, an enlarged view 

 of Crab Grass. B, with small glume attached. C. A, 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 E, 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.) 



