Wild Flowers 379 



As the struggle for existence, the struggle between 

 rival species, has exerted so much influence in the 

 distribution of the Norwegian flora, the following 

 extract from Professor Blytt's ' Essay on the Immigra- 

 tion of the Norwegian Flora,' pp. 35 and 36, may be 

 interesting : — 



' The struggle between rival species has an essential 

 influence in deciding the nature of the locality where 

 any species can grow ; for we frequently see that plants, 

 when exempted from that disadvantage, are very inde- 

 pendent of the conditions of such locality. Thus I 

 have found Parnassia pahtstris (Common Grass of 

 Parnassus), which otherwise is a marsh plant, on the 

 dry shifting sand of Jaederen, thriving excellently in 

 company with Carex arenaria (Sand Sedge). /rfs 

 ])seudacorus (Yellow Flag) is usually a water plant — I 

 have found it several times on dry sand-shores, once 

 even in flower. These species could have scarcely been 

 able to grow on the dry sand, if the covering of the 

 vegetation on the sand had not been so thinly spread ; 

 that is to say, had there teen other species to dispute the 

 plaee vAth them. Several species grow naturally only 

 where they are moistened with snow water ; many 

 species are naturally bound to a salt soil, many to 

 marshy places ; when cultivated, they are found to 

 thrive remarkably well under conditions which we 

 should think would be anything but favourable to 

 them. Thus, in our botanical garden, Catabrosa 

 cdgida is cultivated, and thrives excellently with- 

 out snow water; it is known that shore plants can 

 thrive, when cultivated, without requiring salt ; species 

 which naturally only grow in very marshy places, are 



