THE CONIFEROUS PLANTS OF ITAL^i. 127 



Pumilio and Cembra from the Riesengebirge and Carpathian 

 mountains. 



We see then that on the Alps are found all the Conifers of 

 nortliern and Central Europe without any exception. This fact 

 must be of importance with respect to the history of plants, 

 althougli we cannot prove that all these Conifers have certainly 

 descended from the Alps. 



The Alps, it seems, possess more species than the northern 

 parts of Europe. In the region of the Conifers these species 

 play the same part as in Scandinavia, the north of Russia, the 

 northern plain of Europe, and the mountains of Central Europe. 

 The forests of Conifers are composed of a larger number of indivi- 

 duals, and occupy a much greater extent of country than those of 

 the Alps. In the north, all the Conifers, with the single excep- 

 tion of Juniperus nana, descend into the plains ; the Conifers on 

 the northern slope of the Alps do the same, except the Alpine 

 species Juniperus nana, Pinus Pumilio, and those which, 

 though belonging to the region of the Conifers, approach the 

 Alpine region, as, for instance, Larix europcea and Pinus Cem- 

 bra. On this side they appear not only in the valleys and on 

 the terraces, but at the foot of the mountains ; but on the 

 southern slope, Juniperus communis is the only Conifer inhabit- 

 ing the plains of Lombardy. 



The Alps and Pyrenees have in common Pinus sylvestris, 

 Abies excelsa, pectinata, Juniperus communis and Sabina, and 

 Taxus baccata ; perhaps also, but apparently not, Pinus Cem- 

 bra and Larix europcea, which are eastern forms. The Pyrenees 

 do not possess solely any one species, unless Pinus uncinata is 

 looked upon as a distinct species. 



Among the species of the north of Europe, Larix europcea 

 and Abies excelsa have their southern limit on the south slope 

 of the Alps. The genus Larix stops there also, but the genus 

 Abies is preserved by other species. Pinus sylvestris has, as a 

 general rule, the same limit, but it may be found more to the 

 south ; other species, however, then take its place, so that the 

 genus is preserved. Taxus baccata, Juniperus nana and com- 

 7nunis, are found further to the south, the two former being 

 mountain plants and inhabiting a colder climate. Among the 

 Conifers, the northern limit of which is in the mountains of 

 Central Europe, Abies pectinata and Juniperus Sabina extend 

 also more to the south, but always as mountain plants. Pinus 

 Cembra is not found further south. P. Pumilio, or a form 

 analogous to it, reappears on the Apennines under similar cir- 

 cumstances as regards climate. 



The great plain of the Po possesses no Conifers but Juni- 

 perus communis, which occurs on the heaths and sandy places, 



