290 DOMESTICATED ANIMALS AND PLANTS 



forty-two known species of Euphorbiacea, to which the manioc 

 belongs, are all found wild in South America, and not one of 

 them in the Old World, 1 than which no argument is better. 



The turnip (Brassica campestris). This old favorite of the 

 gardens, the white turnip, and the English field swede are but 

 different varieties of the same species. When we attempt to 

 study them from our present standpoint they introduce some 

 interesting facts, not the least of which are the puzzles of the 

 botanist. 



The turnip is closely related to the cabbage and cauliflower 

 (Brassica oleracea), the mustard, both black and white (Brassica 

 nigra and Brassica alba), and the rape (Brassica napus), so 

 valued for sheep pasturage as to constitute in many sections a 

 staple farm crop. 



All these plants grow wild in southern Europe and Siberia, 

 and are especially abundant in England, Holland, Sweden, 

 Denmark, and Finland. They have evidently but recently been 

 introduced into cultivation, which tallies well with their half- 

 wild behavior and their tendency to develop markedly distinct 

 varieties, as do also cauliflower, Brussels sprouts, kale, and 

 broccoli, — all from cabbage. 



Miscellaneous roots. The list of roots is not long, but is 

 hardly of sufficient importance for detailed treatment in our 

 limited space. The carrot and the parsnip are both of conse- 

 quence, and their wild congeners are common in Europe. The 

 radish, though a garden vegetable, is better able to maintain 

 itself in the wild than is almost any other of our cultivated 

 plants, as any one can testify who has had occasion to deal with 

 it as a weed. Like the horse-radish, it is a native of Europe, 

 where it has long been cultivated. Salsify, which grows wild 

 along the Mediterranean, is less cultivated than formerly, and 

 seems to be one of those plants that is being abandoned and 

 destined to extermination unless it can maintain itself in the 

 wild, which it seems well able to do. 



1 " Origin of Cultivated Plants," p. 62. 



