162 4. CRUCIFER.E. 



Agrarian region. Inferagrarian — Superagrarian zones. 



Descends nearly to the coast level, in the Peninsula. 



Ascends to 100 or 200 yards, in England. 



Range of mean annual temperature 51 — 46. 



Colonist. Agrestal and Septal. Not a plant by any 

 means generally common, although apparently scattered 

 almost the whole length of Britain. It is sufficiently pro- 

 bable, however, that the fom* provincial vacancies will 

 eventually be filled in ; and it may be incorrect to bring 

 down the county census below 70. Perfectly established, 

 though not clearly a native ; and, indeed, decidedly more 

 like an immigrant than is S. arvensis ; for there can be no 

 doubt that many of its localities have originated fi-om cul- 

 tivation. 



118. SiNAPis NIGRA, Linn./cc i^//'./^/.Jj^^, 



Area 1 2 3 4 5 6 7 8^ *" H * 13 14. 



South limit in Cornwall, Isle of Wight, Kent. 



North limit about Glasgow and the Firth of Forth. 



Estimate of provinces 14. Estimate of counties 50. 



Latitude 51 — 56. English type of distribution. 



Agi-arian region. Inferagi-arian — Midagrarian zones. 



Descends to the coast level, in the Peninsula. 



Ascends to 50 or 100 yards, in England. 



Range of mean annual temperature 52 — 48. 



Native. Viatical, &c. Occasionally by road-sides and 

 on cUffs by the sea-coast, this species has much the ap- 

 pearance of being tmly native ; though a doubt may arise 

 on the subject. As it grows, apparently native, on the 

 isles of the Firth of Forth, something above the latitude of 

 56,° another degree might have been added to its range, 

 and the East Highland province to its area of distribution ; 



