320 



Exotic Conifers in Britain. 



of post-glacial times have persisted right through the centuries 

 that separate the Neolithic period from the present day, and 

 that such species are therefore, in the strict sense of the term, 

 indigenous to Britain. The following is the list (omitting mere 

 shrubs such as Prunus spinosa, Viburnum opulus, Sambuais 

 nigra, Cornus sanguinea, Salix cinerea, &c.) : — Ilex Aqui folium, 

 Acer campestre, Prunus domestical Prunus Avium, Prunus Padus 

 Pyrus Aucuparia, Pyrus communis, Crataegus oxyacantha, 

 Fraxinus excelsior, Ulmus montana, Betula alba, Alnus glutinosa, 

 Corylus Avellana, Quercus sessilifiora, Quercus peduuculata, 

 Fagus sylvatica, Salix caprea, P opulus tremula, Taxus baccata, 

 and Pinus sy Ives iris* 



A few are believed to have been introduced by the Romans, 

 eg., fuglans regia, Castanea vesca, Acer P seudoplatanus, Tilia 

 europaea ; while others found their way to Britain in the sixteenth 

 or seventeenth centuries, eg., AescuLus Hippocastamtm, P opulus 

 alba, Picea excelsa, Abies pectin ata, Larix europaea. Although 

 the last-named was introduced about the middle of the 

 seventeenth century, it was not till the second quarter of the 

 eighteenth century that its cultivation, especially in Scotland 

 was undertaken on a large scale. 



The introductions of the nineteenth century are much the 

 most numerous and interesting, and it is chiefly these that occur 

 to our mind when we speak of the acclimatisation of exotics. 

 Before, however, reviewing these recent introductions, it may be 

 well to look for a little at the climate of Britain, the peculiar 

 character of which has proved so favourable to tree-growth. 



The climate of Britain is characterised by the comparative 

 mildness of the winters and the coolness of the summers. If 

 these two factors varied to a like extent, the mean temperature 

 of London would be the same as that of other places in the same 

 latitude, say, Warsaw ; but, instead of this, we find the mean, 

 temperature of London to be the same (about 49*5' deg. F.) as 

 that of Vienna, which is situated over 3 deg. of latitude further 

 south. The contrast with Munich is even more striking, the 

 mean annual temperature of this city being about 4 deg. F. 

 below that of London. This means that the mildness of the 

 English winter is relatively more pronounced than the coolness 



* Clement Reid. Ike Origin of the British Flora. 



