468 



WEED FLORA OF IOWA 



Fig. 334. 



Figure 334A 

 A, Corn Gromwell (Lithospermum arvense) . 



A, different 

 nutlets, B, one bearing the flower-receptacle and portion of the 

 the natural size of the larger nutlets. 



B, Viper's Bugloss (Echium vulgare). 

 (A, after Hillman, Bull. Mich. Agr. Exp. Sta. ; B, drawn by L. R. Collins.) 



Viper's Bugloss (Echium vulgare L.). 



Nutlets erect, ovoid, one-eleventh in. in length, back distinctly 

 convex; seed straight or curved; outer face with distinct ridge; 

 surface rugose ; color white, base flattened. 



VERBENACEAE, VERVAIN FAMILY. 



Large-bracted Vervain (Verbena bracteosa Mx.). 



Nutlets cylindrical, 3-sided, outer face convex, one-tenth in. in 

 length, outer face rugose at upper end, lower end marked by lines, 

 inner face pitted, scar somewhat elevated, whitish. In seeds of 

 clovers and grasses. 



_**:. 



Figure 335A 



Figure 335B 



Fig. 335. A. Large-bracted Vervain {Verbena bracteosa). B. Blue Vervain 

 (Verbena hastata). A, the outer face, and B, the inner face of a nutlet ; the 

 latter shows the whitish, spongy scar at the base. C, a group showing the 

 natural size. D, a section of a nutlet, taken lengthwise. 

 (A, drawing by C. M. King; B, after Hillman, Bull. Nev. Agr. Exp. Sta.) 



