444 



WEED FLORA OF IOWA 



Radish {Baphanus sativus L.). 



Seed spherical, ovate to oval, frequently angular, one-eighth to 

 one-fifth in. in length, minutely pitted, brownish with glaucous or 

 shining surface; sear inconspicuous, usually surrounded by small 

 dark area ; radicle near sear, prominent. 



Fig. 292. Radish (Raphanus sativus^, two different views. 

 (Drawn by C. M. King.) 



White Mustard {Brassica alba Boiss.). 



Seed nearly spherical, occasionally somewhat oblong, one-twelfth 

 to one-ninth in. long, light colored, reticulations inconspicuous; 

 scar whitish, projecting; seed coats mucilaginous when wet. 



^^« b e 



Figure 293A Figure 293A Figure 293B 



Pig. 293. A. White Mustard (.Brassica alba). B. Charloclc (Brassica arven- 



sis). a, tip of i5od ; b, seeds enlarged, and natural size; c, cross section. 

 (A, drawings by Ada Hayden and L. R. Collins; B, after Hillman, Bull. Mich. 



Agr. Exp. Sta.) 



English Charlock {Brassica arvensis (L.) Ktze.). 



Seed nearly spherical, sometimes oblong, one-fourteenth to one- 

 twelfth in. in diameter, marked with fine ridges, reticulated or 

 honeycombed in appearance, light brown or grayish, with paler 

 appearance; scar whitish, an elevated point at one end of the 

 seed ; embryo large ; cotyledons conduplieate. Only a small amount 

 of mucilage produced in presence of water. 



