470 



WEED FLORA OF IOWA 



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HIP <w 





Figure 337 A Figure 337B 



Fig. 337. A. Catnip (Nepeta cataria). A, views of various seeds (nutlets), 

 three showing the scar-marking. B, one having the nutlet wall partially 

 broken away, exposing the seed proper. C, a nutlet in longitudinal section, 

 showing the embryo. D, group showing the natural size. 

 B. American Germander (Teucrium canadense). 

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



Horehound (Marrubium vulgar e L.). 



Seed ovate, one side convex, flattened side divided into 2 faces 

 by strong central ridge ; one-twelfth of an inch in length ; brownish 



*9* 



Figure 338A 



Figure 33SB 



Fig. 338. A. Giant Hyssop (Agastache scrophulariaefolia). 



B. Common Horehound (Marrubium vulgare) ; a, angled face; b, convex face; 



c, longitudinal section ; d, transverse section ; e, natural size of seed. 



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



or blackish, with straw-colored markings; scar inconspicuous, in a 

 slight depression somewhat paler in color than seed. 



Self-heal (Prunella vulgaris L.). 



Nutlets ovoid, faces convex, marked by longitudinal grooves; 

 one-twelfth of an inch in length; smooth, shining; color brown; 

 small bud marked by white scar appendage. Found in red clover. 



Motherwort (Leonurus cardiaca L.). 



Nutlets 3-sided, occasionally flattened, 1.10 in. long, smooth ex- 

 cept upper end, which is papillose; minutely roughened; straw- 

 colored to brownish. Found in cultivated grass seed. 



