A SEED KEY TO COMMON WEEDS 379 



9. With a slight groove down each side, va- 

 riously colored. Sisymbrium officinale Scop. 41 

 9. Without a groove on each side, surface 



finely reticulate Plantago major L. 77 



7. Quite uniform in diameter. 



8. With a slight groove down each side, va- 

 riously colored. .Sisymbrium officinale Scop. 41 

 8. Without a groove on each side. 



9. Almost circular in cross section, surface 



with rectangular markings 



Hypericum perforatum L. 58 



9. Not circular in cross section, surface finely 



reticulate Plantago major L. 77 



6. Surface not shining. 

 7. Compressed. 



8. With a groove on each side. 

 9. Groove indicated by a loop or double line, 



not over 1.3 mm. long (fig. XL) 



Capsella Bursa-pastoris L. Medic. 39 



9. Groove indicated by a single line. 



10. Groove running out on to one end 



Sisymbrium officinale L. Scop. 41 



10. Groove ending on the face of the seed, 



broader Lepidium ruderale L. 38 



8. Without a groove on each side. 

 9. Surface finely reticulate. .P'.antago major L. 77 

 9. Surface not reticulate. 



10. Light straw-colored and spindle-shaped. 

 11. Scar on one side extending about one- 

 half length of seed, seed not under 1.6 

 mm. long. . . .Digitaria sanguinale Scop. 1 

 11. Scar on one side short, not more than 

 one-fourth length of seed, seed not 



over 1.2 mm. long 



Agrostis alba Schrad. 7 



10. Not light straw-colored or spindle- 

 shaped. 

 11. Not at all kidney-shaped, usually dark 



brown to black, Plantago Rugclii Dene. 78 



11. Usually kidney-shaped and usually not 



dark brown to black. 



12. With a short distinct elevation near 



scar reaching beyond the normal 



outline of the seed (fig. XXXIII) 



Meclicago lupulina L. 51 



12. Without a short distinct elevation 

 at scar extending beyond normal 

 outline of seed. 



