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; scar inconspicuous, usually surrounded by small 

 dark area; radicle near scar, 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. 



Fig 

 (A, 



Figure 293A Figure 293A Figure 293B 



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

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

 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 conduplicate. Only a small amount 

 of mucilage produced in presence of water. 



