COMMON GARDEN PLANTS 117 



ish, water cress, and mustard are other members 

 of the family that are not quite so closely related. 



The members of this group occupy a position 

 of considerable importance in the vegetable 

 garden ; chiefly, however, because of their various 

 flavors rather than because of their nutritious 

 value. There is comparatively little nourish- 

 ment in the substance of any of them, except the 

 cabbage. 



From the standpoint of the plant developer, 

 the members of the cabbage tribe have excep- 

 tional interest not so much because of possibilities 

 of future development as because of what they 

 reveal of past development. 



If, as is believed, they have all sprung from a 

 single species and within comparatively recent 

 times, they afford highly interesting illustrations 

 of the varied lines of development that the 

 offspring of a single plant may be induced to 

 follow. 



Thus the edible head of the cauliflower and 

 broccoli consist in reality of thickened and con- 

 solidated flower parts. The edible part of the 

 kale consists of expanded but tender leaves. 

 Brussels sprouts are thickened buds developed in 

 the axils of the leaves. The cabbage is merely a 

 single monstrous bud, with its leaves unex- 

 panded. And in the kohl-rabi perhaps the most 



