490 



WEED FLORA OF IOWA 



Fig. 365A 



Fig. 3650 



Fig. 365. Achenial hairs of Beggar-ticks. A. Bidens frondosa. B. Bidens 



cernua. C. Bidens aristosa. 



(Drawings by Mary A. Nichols.) 



Sneezeweed (Helenium autumnale L.). 



Achenes straw-colored, with several longitudinal ribs, length 1 

 mm., breadth 0.3 mm. at apex, toward which the achene widens; 

 surface bears scattered appressed hairs; pappus several chaffy 

 points on margin of truncate apex. 



Fetid Marigold (Dyssodia papposa (Vent.) Hitchc). 



Achene slender, 4-angled ; length 3 mm., width at truncate apex 

 .75 mm. ; black, with numerous, scattered, appressed black hairs ; 

 pappus a row of chaffy scales, dividing into numerous, rough, 

 bristly hairs ; 3 mm. long. According to Mr. Fracker, the achenial 

 hairs are simple and duplex, the tip in duplex hairs deeply cleft. 



