CHAPTER XXIII 



ON THE ARCTIC ELEMENT IN SOUTH TEMPERATE FLORAS 



European Species and Genera of Plants in the Southern Hemisphere — 

 Aggi-essive Power of the Scandinavian Flora — Means by which Plants 

 have Migrated from North to South — Newly moved Soil as Affording 

 Temporaiy Stations to Migrating Plants — Elevation and Depression of 

 the Snow-line as Aiding the Migration of Plants — Changes of Climate 

 Favourable to IMigration — The Migration from North to South has been 

 long going on — Geological Changes as Aiding Migration — Proofs of 

 Migration by way of the Andes— Proofs of Migration by way of the 

 Himalayas and Southern Asia — Proofs of ^Migi-ation by way of the 

 African Highlands — Supposed Connection of South Africa and Australia 

 — The Endemic Genera of Plants in New Zealand — The Absence of 

 Southern Types from the Northern Hemisphere — Concluding Remarks 

 on the New Zealand and South Temperate Floras. 



We have now to deal with another portion of the New 

 Zealand flora which presents perhaps equal difficulties — 

 that which appears to have been derived from remote parts 

 of the north and south temperate zones ; and this will lead 

 us to inquire into the origin of the northern or Arctic 

 element in all the south temperate floras. 



More than one-third of the entire number of New 

 Zealand genera (115) are found also in Europe, and even 

 fifty-eight species are identical in these remote parts of 

 the world. Temperate South America has seventy-four 

 genera in common with New Zealand, and there are even 

 eleven species identical in the two countries, as well as 

 thirty-two which are close allies or representative species. 



