50. POLEMONIACE^. — 51. CONVOLVULACE/E. 179 



f^e/f./// / /^^^ 728. PoLEMONlUM CiERULEUM, Linn. 



Area * (2 3 * 5 * 7) 8 * 10 (11) 12 (13 14 15 16). 



South limit in Derbyshire. 



North limit in Yorkshire, Westmoreland. 



Estimate of provinces 3. Estimate of counties 3. 



Latitude 53 — 55. Local type of distribution. 



Agrarian region. Midagrarian — Superagrarian zones. 



Descends to 150 yards, more or less, in Trent. 



Ascends to 300 yards, more or less, in Huraber. 



Range of mean annual temperature, say 46 — 45. 



Native. Rupestral, &c. There is difficulty and uncer- 

 tainty in attempting to illustrate the distribution of this 

 plant by the fixed formula. It has become established, 

 more or less completely, in many spots where we cannot 

 regard it as otherwise than introduced ; and besides the 

 uncertainty which must arise from this circumstance, I feel 

 very imperfectly prepared to state its range of altitude, 

 and consequently that of climate, in the provinces where 

 it may be pronounced certainly indigenous. 



/V/ /^/^.^^ 729. Convolvulus ARVENsis, Linn. 



Area 1 2 3 4 5 6 7 8 9 10 1 1 * 13 14 15 * * 18. 

 South limit in Cornwall, Isle of Wight, Kent. 

 North limit in Orkney, Moray, Aberdeen. 

 Estimate of provinces 16. Estimate of counties 60. 

 Latitude 50 — 60. British type of distribution. 

 Agrarian region. Inferagrarian — Superagrarian zones. 

 Descends to the coast level, in the Channel. 

 Ascends to 100 or 200 yards, in England. 

 Range of mean annual temperature 52 — 46. 



N 2 



