22 SCIENTIFIC SURVEY OF YORK AND DISTRICT 



IV. 



YORKSHIRE PLANT ECOLOGY 



BY 



T. W. WOODHEAD, Ph.D. 



Nearly a century ago, John Phillips, one of the founders of the British 

 Association ,1 gave an outline of the geology and vegetation of Yorkshire 

 which has greatly influenced the writings of subsequent workers. He 

 pointed out that the county provides an ideal area for the study of vegeta- 

 tion in that it contains within its boundaries an almost unequalled range 

 of habitat conditions, and strata ranging from the Silurian slates of 

 Sedbergh, the calcareous and siliceous series of the carboniferous system, 

 through a succession of beds to deposits of pleistocene times. This 

 area has attracted many workers, and the flora of the three Ridings has 

 been admirably described by John Gilbert Baker for the North Riding, 

 F. Arnold Lees, the West Riding, and J. F. Robinson, the East Riding. 

 The vegetation of the Pennines has been mapped and described by 

 W. G. Smith, W. M. Rankin, C. E. Moss, and F. J. Lewis. F. Elgee 

 has described the Clevelands, and the vegetation of that area has been 

 mapped by W. G. Smith, but the maps remain unpublished. On 

 these works the following account is mainly based, and to them readers 

 are referred for fuller details ; I am also indebted to Prof. Goode for an 

 account of the East Riding. 



The Pennine uplands form the western border of the county. In 

 the extreme north-west is Upper Teesdale followed by the north-western 

 calcareous dales, the rest consisting of the gritstone and coal-measure 

 country of the middle and southern Pennines. Upper Teesdale is part 

 of the Cross Fell massif, and Mickle Fell, 2,591 ft., is the highest part 

 of the county and is of interest in that it formed part of an extensive 

 nunatak area during the glacial maximum, hence provides many interest- 

 ing problems for the botanist, and is noted for its arctic alpine rarities 

 and species of closely restricted range, some of which may be relics of 

 a preglacial flora. Species of special interest are Thalictrum alpinum, 

 Draba incana, Potentilla alpestris, Dryas octopetala, Primula farinosa, 

 Bartsia alpina, Pyrola secunda, Polygonum viviparum, Tofieldia palustris, 

 and Equisetum pratense. 



Especially interesting on account of their limited distribution in Britain 

 are Helianthemum canum, Potentilla fruticosa, Saxifraga Hirculus and 

 GeJitiana verna ; the wonderful blue of the last on these Fells suggests 

 a Swiss Alpen-weisen in summer. 



The Tees, which forms the northern limit of the county, enters at 



1 See Chap. XV. 



