MEYENS PHYTO-GEOGKAPHICAL ZONES. 693 



B. — TEMPERATE ZONE. 



3. Sub-tropioal Zone. — This extends from the tropics, 23° to 34° 

 of latitude. Mean temperature 62J° to 71^°; summer temperature, 

 73^° to 82^°. There are many tropical fruits in this region. The 

 winters are mild, and vegetation is green throughout the year. In 

 the northern division of the zone, Pabns and Bananas grow on 

 the plains. The Date-palm, Doom-palm, Chamserops Palmetto, many 

 succulent Mesembryacese and CrassulacesB, arborescent Euphorbias, 

 Camellia, Thea, Aucuba, and Magnolias, are met with. In the southern 

 division are Proteacese, Myrtaceae, Epacridacese, Ericacese, many Com- 

 positse, Diosmese, Zamias, and Cactacese. 



4. The warmer Temperate Zone. — It embraces the space between 

 34° and 45° of latitude, including the southern part of Europe, Asia 

 Minor, north of China, and Japan. Mean temperature, 53 J° to 62|°. 

 Summer temperature in North America,'77° ; in Europe, 75;^° to 68° ; 

 in Eastern Asia, 82;|° ; Winter temperature in the New World, 44|° 

 to 32J° ; in Europe, 50° to 34f° ; in Eastern Asia, 26|°. Many sub- 

 tropical forms occur. Evergreen Dicotyledonous trees and shrubs, 

 Cistuses, many species of Ericacese, Lauracese, and Myrtaceae, and the 

 Vine, are met with. In some parts of the zone, Solidagos and Asters, 

 Magnolias and Smilacese, abound ; while in others there are represent- 

 atives of the Mimosa form, Myrtace» and Proteacese. 



5. The cooler Temperate Zone. — This includes a belt from 45° to 

 58° latitude. Mean temperature, 43° to 53J°. Minimum summer 

 temperature on the West Coast, 56|° ; in the interior of the Continent, 

 68°; minimum winter temperature in the interior of Europe, 14°. 

 England, the north of France, and Germany, supply the characteristics 

 of the vegetation of this zone. It embraces the region of UmbeUiferse, 

 and Cruciferse of Schouw. Meyen selects plants having a more marked 

 physiognomic effect, such as ordinary Dicotyledonous trees, along with 

 Abietinese, and heaths covered with CaUuna vulgaris. 



6. The Subarctic Zone. — This reaches from 58° latitude to the 

 arctic circle, 66°. Mean temperature, 39|° to 43°. Summer tem- 

 perature in the New World, 66^°; in the Old World, 60|° to 68° ; 

 Wintertemperatureof the former, 14°; of the latter (Western Europe), 

 24f ; of the interior of Kussia, 10|^° to 14°. It is characterised by 

 Firs and WUlows in the northern hemisphere. 



C. PEIGID ZONE. 



7. The Arctic Zone. — This extends from the Arctic circle, 66° to 

 72°. Mean temperature, 28J° to 32°, and towards the eastern and 

 continental portions, far Tbelow the freezing point. The Birch, and 

 some Coniferse, may be said to characterise this zone. We meet 

 also with representatives of the genera Andromeda, Myrica, Alnus, 

 Ehododendron, and Salix. 



