DR. HOOKER ON THE DISTRIBUTION OF ARCTIC PLANTS. 



261 



Deyeuxia Langsdorffii. 

 Hierochloe alpina. 

 Colpodium latifolium. 



Colpodium pendulinum. 



fulvum. 



Dupontia Fisheri. 



Alopecurus alpinus. 

 Deyeuxia deschampsioides. 



Lapponica. 



strigosa. 



It is curious to remark how many of these boreal European plants, which are absentees 

 in the Alps, have a very wide range, not only extending to the Himalaya and North 

 China, but many of them all over Temperate North America ; only one is found in the 

 south temperate zone. In the present state of our knowledge we cannot account for the 

 absence of these in the Alps ; either they were not natives of Arctic Europe immediately 

 previous to the glacial period, or if so, and they were then driven soutli to the Alps, they 

 were afterwards there exterminated ; or, lastly, they still inhabit the Alps under disguised 

 forms, which pass for different species. Probably some belong to each of these categories. 

 I need hardly remark that none inhabit Europe south of the Alps, or any part of the 

 African continent. 



The List of Arctic American and Asiatic species which do inhabit the Alps of Europe, 

 but not Arctic Europe, is much smaller. Those marked t are Scandinavian, but do not 

 enter the arctic circle. 



Anemone patens. 



alpina. 



narcissiflora. 



fRanunculus sceleratus. 

 fAconitum Napellus. 

 fArabis petrtea. 

 fCardamine hirsuta. 



Draba stellata. 

 fThlaspi montanum. 

 tLepidium ruderale. 

 tSagina nodosa. 

 fLinum perenne. 



Phaca alpina. 

 fAstragalus hypoglottis. 



fSpirasa salicifolia. 

 tPotentilla fruticosa. 



Potentilla serieea. 

 fCeratophyllum deniersum. 



Bupleurum ranunculoides. 

 tViburnum Opulus. 



Galium rubioides. 

 t saxatile. 



Ptarmica lalpina. 



Aster alpinus. 



Gentiana prostrata. 



Polygonum polymorphum. 



Corispermum hyssopifolium. 



Alnus viridis. 



Pinus cembra. 

 tSparganium simplex. 

 tTypha latifolia. 



Carex ferruginea. 



supina. 



stricta. 



t pilulifera. 



fScirpus triqueter. 



Deyeuxia varia. 



Sj3artina cynosuroides. 

 tGlyceria fluitans. 



Hordeum jubatum. 



Botanical Districts within the Arctic Circle. 



The following are the prominent features, botanical, geographical, and climatal, of 

 the five districts of the arctic zone : — 



1. Arctic Burope. — The majority of its plants are included in the Lapland and Finland 

 floras ; and, owing to the temperature of the Gulf Stream, which Avashes its coasts, Lap- 

 land is by far the richest province in the arctic regions. The mean annual temperature 

 at the polar circle, where it cuts the coast-line, is about 37°, and the June and September 

 temperatures throughout Lapland are 40° and 37° 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 boun- 

 dary ; for the Ural Mountains do not limit the vegetation, any more than do the Eocky 

 Mountains in America. GmeUn observed more than a century ago that the river Obi in 

 lower latitudes indicates the transition longitude from the European to the Asiatic flora. 



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