536 INTRODUCTION TO PLANT GEOGRAPHY [CHAP. 



Even on the most rugged rocky shores in the Arctic and much of 

 the Subarctic, the euhttoral zone is poorly vegetated in exposed 

 situations owing to the rigours of the chmate and particularly to 

 the tearing and grinding of ice, which tides and breakers keep in 

 motion when once it has broken up in early summer. Thus the 

 euhttoral and immediately adjacent sublittoral tend to be ' polished ' 

 by ice-floes and -pups or splinters of ice which waves and currents 

 carry against exposed shores through much of the growing-season. 



Fig. 176. — An arctic foreshore photographed from near low-tide mark, showing 

 euhttoral boulders with sides covered by Brown Algae (chiefly Bladder Wrack, 

 Fticits vesiculosus), whereas their exposed upper surfaces are kept bare by ice- 

 action. Pangnirtung, Cumberland Sound, Baffin Island. 



On the other hand in sheltered situations, including bays and the 

 interior landward shores of nearby islands, and even the sides of 

 boulders (Fig, 176), where there is protection from the ice, species 

 of Fiicus may form a luxuriant investment — ^except in the very Far 

 North where their growth tends to be poor. 



It is, however, in the middle and lower sublittoral, out of reach 

 of floe ice and chiefly at depths of 3-25 metres, that benthic plant life 

 really flourishes in the Arctic — provided the bottom is hard. Here 

 giant Laminariales may form extensive ' beds ', species of Alaria and 



