GEOGRAPHICAL DISTRIBUTION OF TREES. 48 
been given on no mean authority a statement to the effect 
that, in Norway, journeying from north to south, and 
in some parts of the country in descending from a great 
elevation to the valley or plain, we pass through successive 
zones, which have been characterised as the zone of per- 
petual snow, where only a few ice plants, lichens, and 
mosses grow; the zone of the willow and birch ; the zone 
of the pine and fir; the zone of the oak; the zone of 
the beech ; and the zone of the cultivated fields. The 
statement may be useful as a memorandum; but, if 
great stress be upon it, it may break down. I have only 
found it true to the extent that there are here birch weods, 
or forests, reaching further north than any forest of pine 
or fir, though trees of these may be found in the same 
latitude; that willows are found in higher latitudes than 
these ; and that there are forests of fir and pine further 
north than oaks; and oaks further north than beeches; 
and beeches growing further north, and at a high ereleva- 
tion, than general cultivation has extended. But beyond 
an indication of these facts, I think the statement cited 
may mislead. 
To the northernmost zone is assigned, as a character, its 
production of the birch, Betula odorata, Bechet. It flour- 
ishes throughout the whole country; but it is in west 
Finmark that it appears forming veritable forests; else- 
where it is found, as a tree which delights in the light, 
very frequently dispersed over clearings in pine and fir 
forests, and besides, on lands completely cleared of woods. 
The altitudinal limits of this tree are in Southern Norway 
about 1,100 metres; in the diocese of Drontheim from 
600 to 700 metres ; and in Finmark from 300 to 400 metres 
above the level of the sea, The birch is in Norway a tree 
of fine growth, and often takes an elegant form, with the 
exterior branches pendant in long clusters, measuring as 
much as 5 metres, or 17 feet. The birch may attain to 
a great age. It is not rare to meet with birches 
from 20 to 25 metres, 67 to 84 feet, in height, and 1:5 
metres, 5 feet, diameter at the ground. The crown may 
