BOTANICAL CHARACTERS, ETC. 271 



country that do not carry turnips, or, at all events, that 

 would not do so were they properly treated. In England, 

 unfortunately, all agricultural estimates are mere matters 

 of guess-work; in Scotland, until lately, an admirable 

 system of statistics enabled us to speak more positively, 

 and really to know what we were about on our farms. 

 On looking for the turnip acreage in the last returns pub- 

 lished (1857), we find that the total area under rotation 

 tillage was 3,556,572 acres; of this no less than 476,691 f 

 were occupied by turnips ; which, if ,we take the average 

 rotation at six years, would show that fully three-fourths 

 of the tillage soils of Scotland are, under the improved 

 treatment there practised, suitable for turnip cultivation. 

 The turnip belongs to an order of plants widely differing 

 from those we have already discussed an order which, 

 however, furnishes to agriculture a class of plants well-nigh 

 equal in number and in importance to either of the others. 

 The name '' Cruciferse " has been given to the "order," 

 from the cruciform shape of its flowers; and the "genus" 

 which comprises the plants we have chiefly to take into 

 consideration is termed by the botanists "Brassica." 

 Among the numerous " species " belonging to this genus 

 the agriculturist is only interested in about five, to which 

 all the varieties of turnip, rape, coleseed, cabbage, &c., 

 are apparently referable. These are as follows: 



1. BRASSICA OLERACEA Cultivated Cabbage. 



2. BRASSICA RAP A Rough-leaved Summer Rape Turnip. 



3. BRASSICA CAMPESTRIS Smooth-leaved Summer Rape Swede Turnip 



Colza. 



4. BRASSICA NAPUS Winter Rape Coleseed. 



5. BRASSICA CAULO-RAP.E Kohl-rabi. 



Dr. Lindley, in speaking of the division of species, says, 

 " How far the various divisions are really to be regarded 

 as distinct species, we are not called upon to determine. 

 They all breed freely together if in each other's neigh- 



