918 



plant may occur, must always be an approximation. In regions 

 with a Continental climate it is possible to state altitudinal li- 

 mits with some precision, and one can distinguish sharply between 

 lowland and mountain piants. This is the case f. inst. in Sweden 

 and in Eastern Norway^ and to a still greater degree in moun- 

 tainous regions like the Pamir and the Himalaya, which lie in the 

 interior of a great continent. In regions with a temperate insular 

 climate the distinction between lowland and mountain piants is 

 much less apparent, because the majority of the species can also 

 thrive in the lowlands, as a relatively low summer temperature 

 does not afTect them injuriously. This is well known, and has been 

 frequently referred to. A. Blytt (1869, pp. 36— 39) has dealt with it 

 in considerable detail for Western Norway. E. Rostrup in his 

 Færoese flora (1870, p. 18) also refers to it, and enumerates some 

 of the mountain piants, which are found all the way down to the 

 coast. 



In my own list of piants (Ostenfeld 1901 b), I have stated the 

 vertical range of each species, as far as my information allowed. 

 These data are here summarised as concisely as various difficulties 

 will permit. It is however hardly possible to prevent one's own 

 personal opinions from entering in. Thus in selecting a boundary 

 between mountain and lowland, I have chosen to limit the term 

 »mountain« to such species as grow on the mountain-plateaux at 

 least 300 m. above the sea, and oftener ranging up to 500 — 800 m. 

 On the contrary, I do not include as mountain the slopes from the 

 plateaux towards the sea. 



The species are arranged in 5 groups^ as shown in the foUow- 

 ing table: 



206 



I. Species found only in the lowland and the lower 



parts of the mountain-slopes 161 



II. Species found in the lower regions and also ex- 



ceptionally on the mountain-plateaux 45 



III. Species found both in the lower regions and on the moun- 

 tain-plateaux 58 



^ Many mountain piants are carried down to the lowlands by the rivers and 

 are able to maintain themselves there; this is especially the case with bog and 

 swamp piants. 



* In the alphabetical list on pp. 896—902 I have added a reference to those 

 groups to the name of each species. 



