1694 ARBORETUM AND FRUTICETUM. PART III. 
in one season. The duration of the birch is not great, the tree attaining 
maturity, in goad soils, in from forty to fifty years; but, according to Hartig, 
seldom lasting in health till it attains a hundred years. 
Geography. The common birch is a native of the colder regions of the 
old Continent ; and also, as we think (under the form of B. populifolia, 
and other kinds, treated by botanists as species), throughout great part of 
North America. It is found in Asia, in Siberia, as far as the Altaic Moun- 
tains ; and also in the Himalayas; but not in Africa. According to Pallas, the 
birch is more common than any other tree, throughout the whole of the Rus- 
sian empire; being found in every wood and grove, from the Baltic Sea to the 
Eastern Ocean; prospering best in a moist alluvial soil (Aumoso-limosum) ; 
and, as it loves a moderate humidity, it always indicates land fit for the plough. 
In some parts of Russia, immense tracts are covered with this tree alone. In 
the neighbourhood of Moscow, it forms the prevailing tree in all the woods 
belonging to the country residences of the nobles, and it may be seen in the 
foreground of fig. 1551., which is a view of the Lake of Petrovskoyé, which, in 
1814, when we made the sketch, was one of the most celebrated “ English 
pleasure-grounds” in that part of the Russian empire. In Europe, Dr. Agardh 
observes, the region of the birch is bounded only by vegetation itself. It 
is found from Iceland to Mount Etna: in the Icelandic forests its limits are 
only those of vegetation; but on Mount Etna it is not higher than 5600 ft. 
above the level of the sea, its range being about 1000 ft. It is found on the 
whole line of the Apennines, in the kingdom of Naples, (where it commences 
at the height of 4761 ft. above the level of the sea,) and at the height of 
6100 ft. forms little woods. (Comp. Bot. Mag., 1. p. 91.) It isalso found on 
most of the high mountains of the south of Europe; on Mount Caucasus, 
in Bucharia, on the eastern shores of the Caspian Sea; in Kamtschatka, 
in forests at lat. 58° N.; in Dahuria, in Japan, and in West Greenland. (Dec.) 
Von Buch considers the birch to require a mean temperature of about 
26° of Fahr. In Lapland, according to the same author, the line of birches is 
1937 ft. below the line of eternal snow, and 802 ft. above the boundary of the 
Scotch pine. At Hosperdet, in a bay of the Icy Sea, the common birch is a low 
bush; but at Alten it becomes a lofty tree, forming woods. (Schouw in Gard. 
Mag., vol. xii. p. 60.) On the Alps, in Switzerland, it is never found at above 
the height of 4400 ch Alphonse De Candolle in Gard, Mag., vol. xii. p. 234.) 
B. alba appears in North America under the form of B. populifolia, which, 
though by many botanists considered as a distinct species, yet we cannot help 
thinking is nothing more than a very distinct variety of the birch of Europe. 
(See No. 2.) B. pumila and B. glandulosa, also found in North America, are, 
probably, nothing more than varieties of B. alba. In Britain and Ireland, it 
is found almost every where on mountains and in poor sandy soils ; reaching 
