54(3 A. HESSELBO 



land. As far upwards as about 200—400 metres the slopes and 

 Hats are covered with heaths and birch-coppices or bogs respec- 

 tively. Then usnally ioUow steep, bare slopes of gravel or abrupt 

 cliffs, and the plateaus which follow these bear the scanty plant- 

 c'overing of the rocky flat. 



The conditions, however, ditler soniewhat in different parts of 

 the country. In NW. Iceland there is almost no low land with the 

 exeeplion of the narrow stretch of coast along the narrow, deep 

 tjords. The steep, often vertical cliff-faces rise to a height of 500 — 

 000 metres and have a talus of débris (Urd) at their foot, and cliffs 

 rising in terraces occur almost exclusively at the head of some of 

 the tjords. The entire surface at the top of the mountain belongs 

 to the rocky tlat, and the associations characteristic of the latter 

 often occur on the slopes and flåts right down to the level of the 

 sea, especially on slopes facing north. 



In S. Iceland, on the other band, in sheltered valleys, localities 

 are met with as far upwards as 500—600 metres above sea-level, 

 which, according to the composition of the plant-covering, must be 

 referred to the Lowland formations. 



I. THE LOWLAND FORMATIONS. 



The Littoral Bryophyte Vegetation. 



There are only very few species which are restricted lo the 

 innnediate vicinity of the sea, or which grow by preference in 

 the neighbourhood of the coast. Schistidium maritimnm and Ulota 

 phyllantha doublless occur wherever there are rocky coasts, and 

 are rarely found many hundred metres from the coast. They 

 chietly occur along the sea-coast itself, and at the entrance to 

 the larger fjords, and decrease in frequency inwards towards the 

 head of the fjord. Near Berufjordur, for instance, both species are 

 very common around Djupivogur, but are entirely absent from the 

 inner part of the fjord, and this is also the case in Seydisfjordur.. 

 Around the broad Isaljordur they are common as far inwards as Arn- 

 gerdareyri, but are, as a rule, absent from the narrow branch-fjords. 

 Both species grow on the coast rocks, but also frequently desccnd 

 to the ground. On the island of Vestmannaey Ulota was very 

 common on knoils in helds, where the grass-covering had been 

 torn up by the wind, and Schistidium maritimnm has been found 

 in several piaces on damp sandy soil. 



