Text-book of structural and physiological botany / by Otto W. Thomé ... and Alfred W. Bennett.

  • Thomé, Otto W. (Otto Wilhelm), 1840-1925.
Date:
1885
Catalogue details

Licence: Public Domain Mark

Credit: Text-book of structural and physiological botany / by Otto W. Thomé ... and Alfred W. Bennett. Source: Wellcome Collection.

Provider: This material has been provided by University of Bristol Library. The original may be consulted at University of Bristol Library.

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    portions, but increases gradually towards the north. The temperature diminishes very rapidly as we advance north- Avards, the cold waters of the Polar sea having no sufficient outflow southwards through the narrow Behring's Strait and Hudson's Bay. Europe has also the advantage of a less variable maritime climate, from the inland seas penetrating to a greater depth. In consequence of this, New York has the summer-temperature of Rome and the winter temperature of Copenhagen ; Quebec the summer of Paris and the winter of Petersburg. Tlie character of the vegetation is determined by this alternation of summer and winter temperatures. The northern belt includes the zone of Fimcs alba and nigra, which in America replace the European firs. Coniferous forests, the individuals of which are often of an immense size, mixed with a few exogenous trees, mark, in the zone of the Oregon pine, the passage to that of de- ciduous exogenous trees. These forests are distinguished from the corresponding oak- and beech-zones of Europe by the greater variety of their oaks, and by the species of elm, ash, and maple. The forest-zone of the Southern States is, as in South Europe, characterised by evergreen ex- ogenous trees intermixed with representatives of tropical famihes. In its moist summer the climate of these States resembles that of China; the most noticeable crops are cotton, rice, and the sugar-cane. But these advantages are again partially counterbalanced by the sandy and marshy nature of the soil from Louisiana to Virginia, [the Great Dismal Swamp], covered by Fmns aiistralis, and by the almost inaccessible swampy lowlands of the Atlantic coast. Most European crops thrive in North America as well as with us; but the great alternations of temperature are un- favourable to the more tropical species, as the orange. The maize is cultivated to higher latitudes than in Europe, while the cultivation of the grape-vine is scarcely anywhere carried on with much success.