CRUCIFER^E 



161 



longitudinally, and grasping but not surrounding the radicle with 

 their edges ; radicle oblong, suddenly tapering to an obtuse point, 

 shorter than the cotyledons. 



Seedling (fig. 168). 



Hypocotijl erect, terete, glabrous, pale green, 1-5-3-8 cm. long. 



Cotyledons broadly cuneate, bifid, broader than long, unequal 



in size, with two strong, alternate nerves, and one or two short 



ones, entering each 



lobe, glabrous, light 



green, paler beneath, 



petiolate ; average of 



three larger laminae 



12-8 mm. long, 14'9 



mm. wide ; of three 



smaller laminae 11-75 



mm. long, 13-8 mm. 



wide ; petiole shal- 



lowly channelled 



above, convex on the 



back, slightly con- 

 nate at the base, 



glabrous, pale green, 



unequal in length, 



the longer one bear- 

 ing the larger lamina ; 



average length of 



three of the longer 



ones 13-75 mm., of 

 three of the shorter 

 ones 12-58 mm. 



The reason for this peculiar form has been suggested above, 

 pages 31 and 43. 



Stem erect, terete, coarsely hairy with bulbous-rooted hairs ; 

 striated longitudinally or shallowly ridged and furrowed, herbaceous, 

 annual, pale green ; 1st internode 3-5-12-5 mm. long ; 2nd to 4th 

 or more undeveloped. 



Leaves simple, radical and cauline, alternate, exstipulate, petio- 

 late, alternately penninerved, with zigzag nerves more or less in- 

 curved, and entering straight into the marginal teeth or lobes or 

 giving off branches into them, hairy on both surfaces, reticulate, 

 light green above with sunk nerves, paler beneath with prominent 

 nerves, more or less decurrent on the petiole ; petiole semiterete, 



FIG. 168. Brassica nigra. Nat. size. 



