486 



WEED FLORA. OF IOWA. 



twelfth in. long; color dull; smooth or covered with yellowish 

 hairs ; achenes 2 in each bur. 



Cocklebur {Xcmthium strumarmm L.). 



Involucre one in. long; brownish in color; prominently bristly 

 spines curved; achenes 2 in each bur; closely resembles- Z*. can- 

 adense. 



Rough-Ox-eye (Heliopsis scabra Dunal). 



Achenes thick, obtusely 3-4-angled, with truncate summit; one- 

 eighth to one-seventh in. long; margins pubescent; blackish; apex 

 somewhat depi-essed; scar at base light or straw-colored; pappus 

 none. 





Fig. 860A Fig. 860A1 Fig. 360B Fig. 3600 



Fig. 360. Seeds of Heliopsis and Kudbeckia. A, Al, Ox-eye (.Heliopsis scabra'). 

 B. Black-eyed Susan or Nigger-head (.RudhecTcia hirta") ; a, two views of 

 achenes, b, achenes, natural size. C. Coneflower (.Budbeckia laciniata). 



(A, C, drawings by L. Collins; Al, Charlotte M. King; B, after HiUman, Bull. 

 Mich. Agr. Exp. Sta.) 



Nigger-head {Budbedkia hirta L.). 



Achene purplish black, 1.5-1.8 nun. long,' tapering slightly from 

 base to apex ; a distinct ridge at each of the 4 angles of the achene ; 

 each side with fine longitudinal strips; no pappus. 



Cone-flower {Rudbeckia laciniata L.). 



Achenes 4-angled, brownish, truncate, one-fifth in. long; min- 

 utely roughened; upper end with projecting truncate point; apex 

 with an inconspicuous scar. 



Gray-headed Cone-flower (Lepachys pinnata Torr. & Gray). 



Achene short, flattened or angular, one-tenth of an inch long, ,2 

 slightly marginal wings, and 2 intermediate ones, or only 1, convex ; 

 apex whitish, depressed with slight projecting scar; base with 



