332 63. POLYGONACE^. 



931. Polygonum Bistorta, Linn. 



Area 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 (17 18). 



South limit in Devon, Dorset, Sussex, Kent. 



North limit in Isle of Skye, Aberdeen. 



Estimate of provinces 16. Estimate of counties 60. 



Latitude 50 — 58. British type of distribution. 



Agrarian region. Inferagrarian — Superagrarian zones. 



Descends to the coast level, in Peninsula or Channel. 



Ascends to 200 yards, more or less, m Humber. 



Range of mean annual temperature 50 — 46. 



Native. Pratal. Probably introduced to several of its 

 present localities, especially the more northern ; so that 

 there is difficulty or uncertainty in an attempt to show the 

 true geographical distribution of the species. Dr. Neill 

 found it in Orkney, but within or on the site of an old gar- 

 den. The Rev. G. Gordon marks it as a plant of Ross, and 

 also includes it in his Flora of Moray ; but expressly indi- 

 cates it to have been certainly introduced to Moray. Per- 

 haps the type of distribution may be deemed British 

 approximating to Scottish ; the chief prevalence of the 

 species apparently being in the northern provinces of Eng- 

 land. And yet it is not at all a characteristic plant in the 

 flora of boreal Europe, being quite local in Scandinavia. 

 In the southern provinces of England it would seem to be 

 of rare or decidedly local occurrence ; and though I have 

 been in various parts of the Peninsula, Channel, and 

 Thames provinces, I have never met with this species there. 

 Said to grow near Winch Bridge, Teesdale, on the York- 

 shne side of the river ; but I do not know whether the al- 

 titude of this locality exceeds 200 yards. 



