492 "WEED FLORA OF IOWA 



Ox-eye Daisy (Chrysanthemum leucanthemum L.). 



Achenes flattened, club-shaped, straight or slightly curved, one- 

 twentieth to one-tenth in. long, oblong; angles white, with brown 

 interstices ; 5-10-ribbed ; small scar at basal end ; pappus wanting. 



Fig. 368. Seeds of Ox-eye Daisy (Chrysanthemum leucanthemum). A, pre- 

 vailing forms of seeds (achenes) ; B, one in cross section ; C, a group 

 showing the natural size. 



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



Wormwood (Artemisia biennis Willd.). 



Achenes brown, smooth, from 3-4 flattened faces, angled between 

 longitudinally; length .8 mm., width .3 mm., broader at apex than 

 at base. 



# 



'6 



Fig. 369B 



Fit;. 8( 19 A 



Fig. 369. Seeds of Wormwood and Fireweed. A. Wormwood (.Artemisia 



biennis) ; a, achenes, b, natural size. 



B. Fireweed (Erechtites hieracifolia) ; a, achenes, b, natural size. 



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



Fireweed (Erechtites hieracifolia (L.) Raf.). 



Achene linear-oblong, straight, or curved, prominently striate, 

 pubescent, beakless, one-sixth in. in length ; upper end with a white 

 ring, within the ring a slight depression ; scar at the lower end with 

 whitish ring, and a small depressed opening; pappus of numerous 

 white soft, capillary bristles. 



