462 



WEED FLORA OF IOWA 



Figure 324B 



Fia. 324. A and Al. Wild Parsnip (Paatlnaca sativa). B. 'Wild Carrot 

 iDaucua carota). A, the outer (at left) and inner (at right) faces of a 

 seed (carpel). The spines occupy the margin and two rows along the 

 outer face. The slender, hairy ridges alternate with the rows of spines. 

 The' Inner face bears two, separated by a slender ridge or line which is not 

 hairy. B, an oblique view of the outer face of a seed found with clover 

 seed. C and D, views of the inner face of seeds similarly found. E, seeds, 

 natural size. 



(A, after Hillman, Bull. Nev. Agr. Exp. Sta. ; Al, drawing by I* R. Collins ; 



B, after Hillman.) 



ASCLEPIADACJEAB, MILKWEED FAMILY. 



Swamp Milkweed (Asclepias incarnata L.). 



Seeds oval, wing-margined, three-tenths in. in length ; surface less 

 prominently veined than in A. syriaca; raphe marked by distinct 

 ridge; coma attached to smaller end of fine silky hairs. Probably 

 never in commercial seed. 



Common Milkweed {Asclepias syriaca). 



Seeds flattened, oval or elliptical, apical end truncate, three- 

 tenths in. in length, wing-margined; seed and vnng distinctly 

 veined ; the raphe occurs in form of a distinct ridge on inner face of 

 seed ; coma a tuft of silky hairs attached to apical end, easily sepa- 

 rated from seed. Not apt to be found in commercial seed. 



