1915] 



WILLE — FLORA OF NORWAY 91 



species being either unknown in Norway or found only in 

 later deposits, some of them probably not having immigrated 

 until later, together with Picea excelsa. They are Angelica 

 sylvestris, Cakile maritima, Comus suecica (?), Helianthus 

 peploides, Hedera Helix, Ledum palustre (f), Potamogeton 

 crispus, Ranunculus Flammula, R. sceleratus, Sagittaria sag- 

 ittifolia, and Viscum album. 



A. Blytt ('82) assumed that a great many warmth-loving 

 species, constituting what he called the " boreal flora," must 

 have immigrated at this time, especially several xerophilous 

 plants, such as a number of Labiatae, Boragineae, etc. (some 

 of which are now commonly found on the steppes of southern 

 Russia), which still keep especially to warm slates and lime- 

 stones in the Norwegian lowland in the east, the west, and the 



province of Trondhjem. 



Andr. M. Hansen ( '04) draws especial attention to the fol- 

 lowing among these species, constituting what he calls the 

 ' ' Origanum community, ' ' and which grow on open slopes with 

 a very sunny exposure: Agrimonia Eupatoria, Androsace 

 septentrionalis, Arenaria serpyllifolia, Calamintha Acinos, 

 Campanula Cervicaria, Carex muricata, Centaurea Scabiosa, 

 Dianthus deltoides, Echinospermum lappula, Origanum vul- 

 gare, Plantago media, Polygala amara, Ranunculus Polyan- 

 themos, Torilis Anthriscus, Trifolium medium, Turritis 

 glabra, Verbascum nigrum, and V. Thapsus. As they grow 

 upon dry slopes, it is not very probable that remains of them 

 will be preserved in peat-bogs or elsewhere. Paleontologic- 

 ally, therefore, their immigration cannot be determined, bnt 

 something may be concluded as to their occurrence in the 

 present day; for it appears that this warmth-loving plant 

 community has its most connected province of distribution 

 from the lowlands of the southeast of Norway, on the warm 

 slates through Valdres and Gudbrandsdal, and are then met 

 with once more on the low land of the western fjord valleys, 

 and in the province of Trondhjem. To this last locality there 

 is evidently also an immigration road through Jemteland 

 from the east coast of Sweden. On the other hand, this plant 

 community is wanting throughout so great a part of the 



