384 71. AMENTIFEEiE. 



the published data towards showing the true localities and 

 distribution of P. canescens, as regards either their suffi- 

 ciency or their correctness. 



997. POPULUS TREMDLA, Linn. 



Area general. 



South limit in Devon, Isle of Wight, Kent. 



North limit in Orkney, Hebrides, Sutherland. 



Estimate of provinces 18. Estimate of counties 75. 



Latitude 50 — 60 (61). British type of distribution. 



Agrarian region. Inferagrarian — Superagrarian zones. 



Descends to the coast level, in the Peninsula. 



Ascends to 550 yards, in East Highlands. 



Range of mean annual temperature 51 — 41. 



Native. Sylvestral, &c. More frequent in Scotland and 

 the northern provinces of England, but found occasionally 

 in the south of England. In the Highlands it ascends 

 to 400 yards, and upwards, in several places, but seldom 

 exceeds 500 yards. Like the Alnus and Corylus, this 

 tree also might be considered to ascend slightly above the 

 agrarian region in Scotland. Not reaching to the Shetland 

 Isles, according to Edmondston's Flora, unless that author 

 has mistaken the present species for P. nigra, which latter 

 he does enumerate in his list, although it would seem far 

 less likely than is P. tremula to be found in Shetland. 



998. PopuLUS NIGRA, Limi. 



Area 12345*789 10 11* (13) 14 (15 16) * [18]. 



South limit in Devon, Isle of Wight, ? 



North limit in Northumberland, Edinburgh .'' Lanark ? 



