1694

ARBORETUM AND FRUTICETUM.

PART III.

in one season. The duration of the birch is not.great, the tree attainingmaturity, in good 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 theold Continent; and also, as we think (under the form of B. ympulifolia,and other kinds, treated by botanists as species), throughout great part ofNorth 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, thebirch 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 theEastern Ocean; prospering best in a moist alluvial soil ( kumoso-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. Inthe neighbourhood of Moscow, it forms the prevailing tree in all the woodsbelonging to the country residences of the nobles, and it may be seen in theforeground of fig. 1551., which is a view of the Lake of Petrovskoye, which, in

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1814, when we made the sketch, was one of the most celebrated “Englishpleasure-grounds ” in that part of the Russian empire. In Europe, Dr. Agardhobserves, the region of the birch is bounded only by vegetation itself. Itis found from Iceland to Mount Etna: in the Icelandic forests its limits areonly 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 thewhole line of the Apennines, in the kingdom of Naples, (where it commencesat the height of 4761 ft. above the level of the sea,) and at the height of6100 ft. forms little woods. (Comp, Bot. Mag., 1. p. 91.) It is also found onmost 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 about26° of Fahr. In Lapland, according to the same author, the line of birches is1937 ft. below the line of eternal snow, and 802 ft. above the boundary of theScotch pine. At Hosperdet, in a bay of the Icy Sea, the common birch is a lowbush; 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 abovethe height of 4400 ft. (M. Alphonse De Candolle in Gard. Mag., vol. xii. p. 234.)B. alba appears in North America under the form of B. ympulifdlia, which,though by many botanists considered as a distinct species, yet we cannot helpthinking is nothing more than a very distinct variety of the birch of Europe.(See No. 2.) B. piimila and B. glandulosa, also found in North America, are,probably, nothing more than varieties of B, alba. In Britain and Ireland, itis found almost every where on mountains and in poor sandy soils; reaching