HOOKER ON ARCTIC PLANTS. 209 



IV. — B0TANIC.A.L Districts within the Arctic Circle. 



The followinjr are the prominent features, botanical, geogra- 

 phical, and climatal, of the five Districts of the Arctic zone : — 



1. Arctic Europe.. — The majority of its plants are included 

 in the Lapland and Finland Floras ; and, owing to the temperature 

 of the Gulf Stream, which washes its coasts, Lapland is by for the 

 richest province in the Arctic regions. The mean annual tem- 

 perature at the Polar Circle, where it cuts the coast-line, is about 

 37°, and the June and September temperatures throughout Lap- 

 land are 40° and 57° respectively ; thus rendering the climate 

 favourable both to flowering and fruiting. Spitzbergen belongs to 

 this flora, as do Nova Zembla and the Arctic countries west of 

 the river Obi, which forms its eastern boundary; for the Ural 

 mountains do not limit the vegetation any more than do the 

 Rocky Mountains in America. Gmelin observed, more than a 

 century ago, that the River Obi in lower latitudes indicates the 

 transition longitude from the European to the Asiatic flora. 



Even in this small area, however, there are two floras, corre- 

 sponding to the Arctic-Norwegian and Arctic-Russian. The 

 latter, commencing at the White Sea, though comparatively ex- 

 cessively poor in species, contains nearly 20 that are not Lappo- 

 nian, including Braya rosea, Dianihus alpinus, D. Seguieri, 

 SpircBa chamcedrifolia, Saxifraga hieracifolia, Hieradeum Si- 

 hiricum, Liguria Slbirica, Ptarmica alpina, Gentiana verna, 

 Plcurogyne rotata, and Larix Sibirica. 



There are, further, several Scandinavian plants which cross the 

 Arctic Circle or the east shores of the White Sea, but do not da 

 so in Lapland, as Athamanta Lihanotis, Chrysanthemum Leucart" 

 themum, Bidens tripartita, and others. 



Iceland and Greenland also botanically belong to the Arctic- 

 Lapland province, but I have here excluded both : the former 

 because it lies to the south of the Arctic Circle ; the latter 

 because both its magnitude, position, and other circumstances 

 require that it should be treated of separately. 



As far as I can ascertain, 616 species (Monocotyledons 183, 

 Dicotyledons 433, = 1:2-3) enter the Arctic Circle in this region, 

 of which 70 advance into Spitzbergen ; but no phsenogamic plant 

 is found in Ross's Islet beyond its northern extremity. The 

 proportion of genera to species is 266 :616 (1 :2'3). Of these 

 Arctic-European plants, 453 cross the Alps or Pyrenees to the 

 Mediterranean basin ; a few occur on the mountains of Tropical 

 Africa (including Luzula campestris and Deschampsia ccespi- 

 tosa ) ; and 23 are found in South Africa. 



No fewer than 264 species do not enter the Arctic Circle in 

 any other longitude; and 184 are almost exclusively natives of 

 the Old World, or of this and of Greenland, not being found in 

 any part of North America ; 24 are confined to Arctic Europe 

 and Greenland. 



36122. O 



