342 COLLEGE BOTANY 



The genus Brassica contains B. nigra (black mustard), B. 

 alba (white mustard), B. oleracea (cabbage), B. campestris 

 (field turnip), B. rapa (flat turnip) and B. napus (rape). 



The cultivation and use of mustard was known by the Greeks 

 and Romans fully 300 years b.c. and traveled with the spread 



Fig. 179. — The spherical form of cabbage. 



of Christianity into other parts of Europe and thence through- 

 out the world. It is used extensively as a condiment for dressing- 

 foods, in the making of soaps and for medicinal purposes. 



The cabbages have been derived from the wild cabbage (B. 

 oleracea) (Fig- 1T9) of central and western Europe, but are now 

 grown throughout the greater part of the world. It was used as 

 food for at least 300 years b.c. Among the most important are 

 the common head cabbage (var. capitata), the Brussels sprouts 

 (var. gemmifpyn), the Kohl-rabi (var. caulo-rapa) (Fig. ISO), 

 and the cauliflower (var. botiv/fis) (Fig. 181). 



