586 A. HESSELHO 



Ihjpnum iincinatnm. Hylocomiuin spp., lihacoinitriiini spp. and Thu- 

 idiuDi delicalnhim (S. Icel.). These are often associated wilh several 

 of the xerophilous species, such as Dicraniim sco})ariiim , Friillania 

 Tamariscl, Plilidiiiiu ciliare and Antilrichia ciirtipendula, through which 

 are formed transilional stages to the moss-heaths menlioned beloNv. 

 In South Iceland several of the southern species have their greatest 

 distribution on well-sheltered, grass-covered slopes wilh a southern 

 exposure, for instance Scleropodinm punim, Eiirhynchiiun piliferuiih 

 E. Stockesii, Thiiidium tamarisciimm, T. Philiberli, T. delicatidum and 

 Mijiiim nndnlatiim. 



Birch coppices grow on a rather dry subshaluni. The 

 Nvood-floor is either occupied by grassland or by heather moor, 

 and the Bryophyle vegetation does not dilTer in any respect from 

 that which occurs on a corresponding substratum oulside the 

 coppices. Most frequenth' it consists of Hylocomium spp. in asso- 

 ciation whh Hijpnum iincinntiim and Rhacomitrinm spp. {R. canes- 

 cens and 1\. hijpnoides). 



Bryophyla grow only rarel}' and scantily on tree trunks. Ra- 

 diila complanata and Friillania dilafata have been found in one 

 single spot on a tree trunk, but, as a rule, it is some ground species 

 or other which grows a little way up on the slanting trunks. In 

 some few piaces Rhacomitrinm fascicnlare has been found on tree 

 trunks to which it had spread from neighbouring stones. 



Laugardalsskogur. This coppice, which is open and of 

 about a man's height, has its floor mostly covered with heather 

 moor, with a thick moss carpet composed of Hylocomium parieli- 

 nnin, H. prolifernm, H. triquetrnm, H. squarrosiim, Hypniim iincina- 

 tnm and Rhacomitrinm hypnoides, occasionally Dicrannm scoparinm, 

 Plilidinm ciliare, Lophozia lycopodioides and L. qninqnedentata also 

 occurred. Of quite a similar composition was the moss carpet in 

 almost all the coppices of South and West Iceland. A few other 

 species also belong to this conimunit}^ but are more rarely niet 

 with, for instance Brynm cæspiticinm, Pohlia nntans, P. acnminata 

 and Lophozia barbata. 



Hallormst adaskogur (East Iceland). The floor liere rather 

 varies in nature, and is sometimes covered with heather moor and 

 sometimes with grassland or peat. In heathy soil Hylocomium spj). 

 were dominant in connection with Rhacomitrinm hypnoides, while 

 especially Hypnum iincinatnm grew abundantly on grassy ground. 

 Where it was very shady Timmia anstriaca grew abundantly on knoils. 



