71. AMENTIFER*. 383 



P. alba in a list of plants seen by him in Cantire, Argyle- 

 shire. The Rev. G. Gordon holds it certainly introduced 

 in Moray. It is omitted fiom the Flora of Aberdeen, and 

 vaguely indicated, as a planted tree, in that of Forfarshire. 

 In the Catalogue printed for the Botanical Society of Edin- 

 burgh, it is entered as a native, although veiy rare in their 

 circuit. In the Flora of Berwick, it is mentioned as an in- 

 troduced tree. But Winch holds it to be truly indigenous 

 in the province of Tyne. The genus 'Populus' appears to 

 be altogether omitted fiom the Flora of Yorkshire, likely 

 enough by oversight in the author. P. alba is clearly indi- 

 genous in the southern provinces of England. As Winch 

 states that it grows at a "considerable elevation" on the 

 sides of the moors in the province of Tyne, the range of 

 elevation is carried up to 200 yards, less or more, and into 

 the superagrarian zone, with a mean temperature to cor- 

 respond. 



'^ /^ ^^ / /^a 996. Populus canescens, Sm. 



Area 12 3 4 5478**11** (14). 



South limit in Devon, Kent, ? 



North limit in Northumberland, ? 



Estimate of provinces 10. Estimate of counties 30. 



Latitude 50 — 56. English type of distribution. 



Agrarian region. Inferagi-arian — Midagrarian zones. 



Descends to the coast level, in the Peninsula. 



Ascends to 100 or 200 yards, in England. 



Range of mean annual temperature 51 — 48. 



Native. Sylvestral, Septal. The distribution of this 

 species can be shown even less satisfactorily than that of 

 P. alba, with which latter species it is perhaps often con- 

 fused. I fear that very little reliance can be placed upon 



