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by Decandolle and Sprengel, in The scarcely eighteen degrees of longitude 

 Philosophy of Plants, "there are a from the west of Africa, and which lies 

 great many perfect plants which ex- , a little further south than Congo, has 

 clusively belong to the tropics, which yet no plants, which are tound in those 

 never pass beyond them, and which arc last-named regions. (Roxburgh's List 

 found equally in Asia and Africa, in of Plants seen in the Island of St. He- 

 America and the South Sea Islands, and lena, appended to Beatson's Island of 

 even in New Holland. Although, as St. Helena.) Japan has a great many 

 we have said, these are rather families, plants common to Southern Europe, 

 as Palma; Scitaminea;, JNIuses, Sapin- which, however, are not found in those 

 deae, and Anoneae ; or genera, as Epi- regions of Asia that lie under the same 

 dendrum, Santalum, Olax, Cymbidium, latitude. 



and so forth; yet there are particular We must further remark, that the 



species, which grow in all parts of the eastern countries of the old world, and 



world only between the tropics, as for the eastern shores of America, as far as 



instance, Heliotropium Indicum, Age- 

 ratuni conyzoides, Pistiae stratiotes, 

 Scoparia dulcis, Guilandina Bonduc, 

 Sphenoclea; zeylanica, Abrus precato- 

 rius, Boerhavia mutabilis, and so forth. 



the Alleghany Mountains, have a much 

 lower temperature than the western 

 regions ; and that it is always colder in 

 Siberia and the north-east of Asia, than 

 under the same latitude in Europe 



But most commonly there are other and, that even Petersburgh is colder 

 species, which, under the same degree , than Upsal, and Upsal than Christiania ; 

 of latitude, supply in the new world the j although they all three lie in the six- 

 place of related species in the old. | tieth degree of north latitude. In 

 Dryas octopetala, indeed, grows equal- North America the ditference is still 

 ly upon the mountains of Canada, and greater, and there are commonly fifteen 

 in Europe; but Dryas tenella of Pursh, degrees of Fahrenheit's thermometer 

 which is very like the former, grows, between the temperature of the east 

 only in Greenland and Labrador. In- j and west coast. It hence happens that 

 stead of the Platanus Orientalis, there ! many plants which in Norway grow 

 grows in North America the Platanus , under the polar circle, scarcely reach 



Occidentalis; instead of Pinus Cembra 

 in Europe and Asia, there grows in 

 North America Pinus Strobus ; instead 

 of Prunus Laurocerasus,in Asia Minor, 

 there growls under the same latitude in 

 North America the Prunus Caroliniana. 



the sixtieth degree, on the limits be- 

 tween Asia and Europe. To this class 

 belong the Silver Fir, Mountain Ash, 

 Trembling Poplar, Black Alder, and 

 Juniper. Even in the temperate zone, 

 the vegetation of many trees ceases 



There are many exceptions to this rule, sooner in the east than in the west. In 



however, depending on circumstances 

 that have been already noticed. In the 

 first place, countries are wont to share 

 their Floras with neighbouring regions, 

 especially islands lying under the same 

 latitude, as the Azores possess the 

 Floras of Europe and of Northern Af- 

 rica, rather than those of America, be- 



Lithuania and Prussia, under the fifty- 

 third degree, neither vines nor peaches 

 nor apricots thrive : at least their fruit 

 does not ripen, as also happens in the 

 middle of England. The most remark- 

 able example of this great difference of 

 temperature is furnished by the Mespi- 

 lus Japonica, which grows at Nanga 



cause they are scarcely ten degrees of 'Sacki, and Jeddo, under the thirty-third 

 longitude from the coast of Portugal. I and thirty-sixth degrees of north lati- 

 Sicily, and, still more,Maita, possesses a i tude ; and which also grows in the open 

 Flora made up of those of the South ofj air in England, under the fifty-second 

 Europe and the North of Africa. The degree of north latitude, when it is 

 Aleutian Islands share their Flora with I planted against a wall. — Botanical Re- 



the north-west coast of America, and 

 the north-east of Asia. But the most! 



^iste)-, Vol. V. 

 The same degree of latitude in the 



distant countries, lying under the same southern and northern hemisphere, are 

 latitude, may have the same or a simi- j connected with very different tempera- 

 lar vegetation, while countries or isl- tures, and produce a completely differ- 

 ands which lie between them, have not ent vegetation. This, however, must 

 the least share in this particular Flora, i be understood rather of the temperate 

 The island of St. Helena, which is | and frigid zones, than of the tropical 



