290 DOMESTICATED ANIMALS AND PLANTS 
forty-two known species of Ezphorbiacea, to which the manioc 
belongs, are all found wild in South America, and not one of 
them in the Old World,! 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 (4rassica 
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. 
