384 IOWA ACADEMY OF SCIENCE 



7. Usually winged and with at least 1 short curved 

 projection on the margin, without grooves on 



the sides Ranunculus abortivus L. 36 



5. Not wafer-like or thin at the edges. 

 6. With pronounced lateral ridges. 



7. Distinctly reddish or dark brown in color. 

 8. Regularly 3-angled, not always equilateral . . 



Polygonum aviculare L. 16 



8. Not regularly 3-angled. 



9. Oval, flattened with 2 marked longitudinal 



striations (see description) 



Setaria viridis L. Beau v. 5 



9. 'Irregularly shaped, angles distinct (fig. 



XII) Oenothera biennis L. 59 



7. Not distinctly reddish in color. 



8. With about 9 distinct rounded longitudinal 

 ridges, broadest at apex, light straw-colored 



usually (fig. XXVI) Anthemis arvensis L. 98 



8. Not broadest at apex and with 9 distinct 

 rounded longitudinal ridges. 

 9. Irregularly shaped, black when fully ripe. 



10. Surface finely reticulate 



Plantago major L. 77 



10. Surface not reticulate, granular 



Plantago Rugelii Dene. 7S 



9. Regularly shaped. 



10. With more than 2 longitudinal ridges 



(fig. XXX) Daucus Carota L. 61 



10'. With not more than 2 longitudinal lines. 



11. More than 1.5 mm. long 



Setaria viridis L. Beauv. 5 



11. Less than 1.5 mm. long 



Agrostis alba L. 7 



6. Without pronounced lateral ridges. 



7. With two small oval white scars placed end 

 to end near one end of the seed (fig. XX) . . 



Nepeta Cataria L. 70 



7. Without scars as above. 



8. Ellipsoidal in cross section and almost cir- 

 cular in greatest outline, usually with a nar- 

 row lighter colored wing, angle at edge 



distinct Spergula arvensis L. 27 



8. Not as above. 



9. Markedly angled and irregular in shape. 



10. With a distinct groove on the faces of the 

 seed, quite strongly flattened. 

 11. Groove extending entire length of seed 



Sisymbrium officinale (L.) Scop. 41 



