CHAP. LXXXVI EVERGREEN CONIFERAE 315 



on which trees are growing. Many of these plants are xerophytic in 

 construction. 1 Pimis sylvestris in like manner passes on to moors. It is 

 only the most accommodating and hardy of plants, both arboreous and 

 fruticose, that can grow on such extreme kinds of soil. 



Mixed Coniferous Forest. 



In many coniferous forests there is an admixture of species, for example, 

 in Sweden, of Pinus sylvestris, Picea excelsa, birch-trees, Populus tremula, 

 and others. This admixture of species is apparently more marked the 

 farther one travels to the east in Europe, possibly because the land here 

 has been occupied by plants for a longer time than it has in the north- 

 western parts, and because the migration of species has, for the most part, 

 been from east to west. In the Russian Government of Perm spruce- 

 forest formed by Picea excelsa and P. obovata includes an admixture of 

 Larix sibirica, Pinus Cembra, Abies sibirica, and others, in addition to 

 dicotylous trees. The type of ground-vegetation present depends, as 

 elsewhere, upon the conditions of illumination ; one finds the same 

 carpet of mosses with scattered Spermophyta, belonging even to the same 

 species, as in Denmark, or a rich vegetation of grasses, ferns, perennial 

 herbs, and so forth. 



Other Evergreen Coniferous Forests. 



Various other associations of evergreen coniferous forest exist, some of 

 which are : 



The Siberian primeval forest ('Taiga ') on the upper Lena, according 

 to Cajander, 2 consists of pines, or of larches (Larix sibirica), or of spruces 

 (Picea obovata) ; pine-forest reigns on sunny, dry slopes ; larch-forest on 

 fresher slopes and in the lowlands ; spruce-forest in the moistest valleys. 

 The forest in plains at the mouth of the Lena is very moist, and abounds 

 in epiphytes ; it may be described as larch-moor (Larix dahurica) that 

 has very thin peat. 



The Mediterranean pineta of Pinus Pinea, with their interesting flora, 

 partly xerophilous and partly marshy halophilous. 



The South-European extensive forests 3 of Pinus halepensis, which 

 suppresses the holm-oak (Quercus Ilex) in places where the rocks are 

 tolerably weathered. 



The Mount Lebanon cedar-forest. 



The North American Abies-forests and Pinus-forests, of which the 

 northernmost grow on icy soil and to some extent differ from European 

 coniferous forest in physiognomy. 4 



The Canary Isles have their pinares, which are forests consisting of 

 Pinus canariensis occurring at an altitude of 1,600 to 2,000 metres, especially 

 on the drier, windy, slopes (the laurel-forest selects moist gullies within 

 the cloud-belt). The pinar, Pinus canariensis, has a conical stem, which 

 bears boughs right down to the ground, and thin needles, 15 centimetres 

 long, which hang down in graceful curves. In these pinares one hears 



1 See Chap. XLVI. * Cajander, 1903. 



' Flahault, 1893 J Beck von Mannagetta, 1901. 

 4 Mayr, 1890; Kearney, 1901 ; Whitford, 1905. 



