DR. HOOKER ON THE DISTRIBUTION OF ARCTIC PLANTS. 265 



Picea orientalis. Cypripedium Calceolus. 



Larix Ledebourii. Carex ferruginea. 



In other words, of the 233 Asiatic species, 196 are common to Asia and Europe, 

 22 are confined to Asia and Europe, 25 are confined to Asia and America only ; and 12 

 are confined to Asia, of which 3 are peculiar to the arctic circle. 



The rarity of Graminea3 and especially of Cyperacese in this region is its most excep- 

 tional feature; only 21 of the 138 arctic species of these orders having hitherto been 

 detected in it. Cryptogamic plants seem to be even more rare ; Woodsia ilvensis and 

 Lastrea fragrans being the only Filices hitherto enumerated. Eurther researches along 

 the edge of the arctic circle would doubtless add more Siberian species to this flora, as 

 the examination of the north-east extreme would add American species, and possibly lead 

 to the flora of the country of the Tchutchis being ranked with that of West America. 



The works which have yielded me most information regarding this flora, are Ledebour's 

 ' Elora Rossica,' and the valuable memoirs of Bunge, C. A. Meyer, and Trautvetter, on 

 the vegetation of the Taimyr and Boganida rivers ; and on the plants of Jenissei river 

 in Von Middendorff's Siberian ' Travels '. Eor their southern extension Trautvetter and 

 Meyer's 'Elora Ochotensis,' also in Middendorif's 'Travels'; Bunge's enumeration of 

 North China and Mongolian plants ; Maximovicz's ' Elora Amurensis ;' Asa Gray's 

 paper on the botany of Japan (Mem. Amer. Acad. N.S. vi.) ; Karelin and Kiriloff's 

 enumeration of Soongarian plants ; Eegel, Bach, and Herder on the East Siljerian and 

 Jakutsk coUections of PauUowsky and Von Stubendorff. Eor the Persian and Indian 

 distribution, I have almost entirely depended on the herbarium at Kew, and on Boissier's 

 and Bunge's numerous works. 



3o Arctic West America. — The district thus designated is analogous in position, and 

 to a considerable extent in climate, to the Arctic European, but is much colder ; as is 

 indicated both by the mean temperature, and by the position of the June isotherm of 41°, 

 which makes an extraordinary bend to the south, nearly to 52° N. L., in the longitude 

 of Behring's Straits. 



It extends from Cape Prince of Wales, on the east shore of Behring's Straits, to the 

 estuary of the Mackenzie river, and as a whole it differs from the flora of the province to 

 the eastward of it by its far greater number both of European and Asiatic species, by 

 containing various Altai and Siberian plants which do not reach so high a latitude in 

 more western meridians, and by some temperate plants peculiar to West America. This 

 eastern boundary is, however, quite an artificial one ; for a good many eastern plants cross 

 the Mackenzie and advance westwards to Point Barrow, but which do not extend to 

 Kotzebue's Sound ; and a small colony of Pvocky Mountain plants also spread eastwards 

 and westwards along the shores of the Arctic Sea, which further tend to connect the 

 floras ; such are Aquilegia brevistylis, Sisynibriim humile, Hutck'msia calycina, JleuQhera 

 Micliardsonii, Crepis nana, Gentiana arctophila, Salix speciosa ; none of which are gene- 

 rally diffused arctic plants, or natives of any other parts of Temperate America but the 

 Rocky Mountains. 



The arctic circle at Kotzebue's Sound is crossed by the isotherm of 23°, and at the 



