26tl FLORA OF THE WEST YORKSHIRE HILLS. 



chief among them in its power to determine the elimination of 

 plants from the flora in either direction, is that competition which 

 is the result of the crowded conditions under which plants exist. 



The ascending series of plants are of Continental or Germanic 

 origin, and are relics of the times when, instead of the separating 

 waters of the German Ocean, there was a land connection between 

 England and the Continent. It was across this now submerged 

 land that they entered and established themselves in England. In 

 time they overran the lower-lying districts, where the conditions of 

 soil and temperature are most favourable to plant-life ; whence, 

 also, the crowding and competition resulting from such conditions, 

 under the long continuance of which they have become inured to 

 competition, and can wage successful war upon hardier plants 

 which are less tolerant of crowding. They like warmth, but do 

 not fear cold, and, therefore, ascend the hillsides, careless of com- 

 petition and of the increasing cold, ceasing only when suitable 

 situations in which to grow are no longer available. Thus, three 

 hundred and thirty-nine of these plants in Yorkshire are found 

 growing between one thousand and seventeen hundred feet, and 

 as many as ninety above nineteen hundred feet, reaching their 

 maximum limits where the soil is driest. 



The following are a selection from those reaching a height of : 



I GOO ft. — Cory da lis claviculata, Gera?tium sangui?teum, Hypericum 



e/odes, Centaurea scabiosa^ Origanum vulgare, Carex 

 Icevigata, Milium effusum. 



I I GO ft. — Calaf?ii?itha dinopodium, Hydrocotyle, Anagallis tenella, 



Carex sylvatica, Fcstuca elatior. 

 1250 ft. — Genista a?iglica, Chrisosplenium alternifolium, Gentiana 



amarella, Phleum praiense, Equisetum limosum. 

 1350 ft. — Hippocrepis comosa^ Car Una vulgaris^ Laduca mural is ^ 



Holcus la7iatus. 

 1 5GG ft. — Arabis hirsuta, Polygonum bistorfa, Asplenium trichomanes, 



Ceterach. 

 i6gg ft. — Poteriu?n sanguis orba^ Parnassia palusiris, Hieradum 



boreale. 

 1 7 GO ft. — Drosera rotundifolia^ Taraxacum^ Carex panicea. 



