THE GENERAL, CHARACTERS OP SEEDS 



445 



"Wild Turnip {Brassica campestris L.). 



Seeds generally nearly spherical or oblong; the caulicle and 

 radicle usually conspicuous along the middle, one-twentieth to ono- 

 twelfth in. in diameter, cultivated forms larger, roughened and 



^^ 



Fig. 294. Wild Turnip (Brassica campestHs). A and B, various forms o( 

 seeds. C, a seed in cross section showing cotyledons and caulicle. D, the 

 embryo. E, seeds, natural size. 



(After Hillman, Bull. Mich. Agr. Exp. Sta.) 



more finely ridged than in B. nigra and B. arvensis; color grayish 

 or brownish; scar at one end. With clover and grass seed. 



Eape {Brassica napus L.). , 



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

 twelfth in. in length, prominently reticulated; closely resembles 

 B. arvensis. Found in mustard and clover seed. 



o 9 



Figure 295A Figure 295B 



Fig. 295. A. Rape (Brassica napus). B. Black Mustard (.Brassica nigra). A, 

 seed enlarged, showing the surface network of dark lines. B, a group of 

 seeds, natural size. 



(A, drawings by Ada Hayden; B, after Hillman, Bull. Mich. Agr. Exp. Sta.) 



Black Mustard {Brassica nigra (L.) Koch.). 



Seed nearly spherical, more generally broadly oblong, one-twen- 

 tieth to one-fifteenth in. in diameter; surface marked with fine 

 ridges; frequently whitish sear at one end; embryo as in B. 



