XXIV THE FLORA OF HALIFAX. 



(4.) Arctic and Alpine species. On the contrary, about 

 thirty-five plants of the parish have reached it from the north. 

 Without entering into the the exact distinction between arctic 

 and alpine plants, or their relation to the glacial epoch, it is 

 sufficiently clear that all such plants in Britain have originated 

 in a migration from Scandinavia, and as. such species exist only 

 at higher levels in more southern latitudes, they are commonly 

 known as alpine or sub-alpine plants. The presence of these 

 here is the chief positive difference between the Halifax Flora 

 and that of the south of England. A few of them, as the bird- 

 cherry, crowberry (Empetvum), cowberry (V. Viiis-Idcea), 

 wood stitchwort and Crepis paludosa, are not uncommon in the 

 parish ; but others are the rarest gems of the flora, and attract- 

 ed the attention of the earliest botanists. The bearberry 

 (Arctostaphylos Uva-ursi), was first discovered in Britain in 1666 

 on Heptonstall Moor ; the cloudberry is only found here above 

 1500 feet, and only extends further south to the Peak and the 

 Welsh mountains in Britain, and northern Germany in 

 Europe ; Trientalis is not found in Britain, south of Halifax. 



These four classes serve to indicate the relationship of 

 British plants to those of other parts of the world. But w T hen 



we come to enquire to what extent the plants 

 Range in of a particular locality are correlated with the 



Britain. flora of all Britain, a somewhat different 



system is more convenient, and the classifica- 

 tion proposed by H. C. Watson, which has become generally 

 accepted, has been adopted in the body of the Flora. Wat- 

 son's names indicate in which part of the country each species 

 is most prevalent. Plants that are found throughout the 

 length and breadth of Britain are said to belong to the ' British 

 type ' ; those which are most abundant in the south of England, 

 and which become scarce, or are absent north of the Midlands, 

 are of the ' English type'. Plants of the ' Intermediate type ' 

 are mainly confined to the north of England ; ' Scottish ' plants 

 have their headquarters in North Britain, and the ' Highland 

 type ' in the Highlands of Scotland. The k Atlantic type ' shows 

 a marked preference for the western coast of Britain, and the 

 ' Germanic type ' is found in the eastern counties of England ; 

 whilst a few species are too local to classify otherwise. Wat- 

 son's Scottish and Highland plants correspond to the Arctic 

 species of the previous classification ; the Atlantic are common 

 to both ; but not only the Watsonian ' Germanic ' type, but the 

 British and English are Asiatic in origin. 



