VIOLET FAMILY 189 



their use also antedates the Christian Era, but they were not 

 grown extensively until early in the seventeenth century. Seed 

 turnips are also kept and grown the second season in the same 

 manner as the cabbage. 



There are several types and varieties of the true or flat 

 turnips. Those with white flesh are most popular, but the 

 yellow-fleshed sorts are also grown. The field turnip, or ruta- 

 baga, has yellowish flesh and is rich in flavor. They produce 

 heavier yields than other turnips. 



' The radish (Eaphanus sativus), the horseradish (Coch- 

 learia armoracia) , the rape (Brassica napa), and the water 

 cress (Nasturtium officinale) and many other valuable plants 

 belong to this family. Most of them originated in the tem- 

 perate regions of Europe and Asia, and their use and cultivation 

 dates back to a very early period in history. 



All of these plants are grown from the seeds which are 

 usually sown direct in the soil in which they are to be grown. 

 The water cress is usually started by transplanting from one 

 locality to another. The mustards frequently escape cultiva- 

 tion and become troublesome weeds. This family also includes 

 wild radish, field cress and many other weeds which are more 

 or less troublesome. However, most of them are annuals or 

 biennials and can be controlled by using a crop requiring fre- 

 quent cultivation or if growing in wheat or oats by spraying 

 with sulphate of iron. 



VIOLET FAMILY 



Flowers perfect, irregular, axillary, usually solitary, two 

 bracts at base or near the middle of each pedicel. Five sepals 

 which are usually free and persistent; five petals which are 

 hypogynous and alternate with the sepals, unequal in size, the 

 lower one forming a hollow spur ; five stamens inserted on lower 



