48S 



WEED FLORA OF IOWA 



Fig. 362A Pig. 362B 



Fie. 362. Seeds of Sunflowers. A. Prairie Sunflower (.BeUantJms petiolaria). 



B. Wood Sunflower (.HelUmfhua atrumoaus) . 



(Drawings by I* R. Collins.) 



Wild Sunflower {Helianthus strumosus L.)- 



Achenes obovate, flattened, several fine lines and a longitudinal 

 ridge on each side, one-sixth to one-fifth in. long, nearly glabrous: 

 yellowish or light brown, finely mottled, except near apex and base 

 which are lighter in color; lower end marked by small distinct 

 soar, occurring in a notch; upper end bearing large circular scar; 

 cotyledons 2, large,, fleshy. 



Fig. 363A 



Fig. 363B Fig. 3630 



Fig. 363. Achenial hairs of Sunflower seeds. 



Fig. 363D 



A. Artioholte (.Helianthus tuber- 

 osua). B. Prairie Sunflower (.BeUanthua occidentalis) . C. Common Sun- 

 flower (.Helianthua annuua). D. Prairie Sunflower (.HeUanthua petiolaria). 

 (Drawings by S. B. Fracker.) 



