504 A. HESSELBO 



to soil present certaiii i)oiiils ol' resembhince to Ihe mountain heights, 

 as the snow in the deep clefts, the bottoni of which is never renchcd 

 bj^ the rays of the sun, oftcn remains till late into the summer. The 

 occurrence of var. tenelhim is more peculiar. It has been found only 

 in S. Iceland, \yhere it grew exclusively on dry or slightly damp blocks 

 of tuff in the lowhinds. But only near Scljaland did a few small tufts 

 occur on a block of tutT at an altitude of about (500 metres. Near 

 Drangshlid it grew abundantly on the fallen blocks of rock al the foot 

 of the rock-wall behind the farm. There in Company with Hypniim 

 ciij>ressiforme, Ccratodon, Didymodon rnbellus , Rharomitrinin fasciculare 

 and Bnjiim argenteum it formed tufts of varying size on the top of the 

 blocks in dr}' situations. Near Barkarstadr it was found on a sonie- 

 what damp tuff-face, and creeping over fallen blocks of rock, in asso- 

 ciation with Pohlia criida, P. y randiflora, Aiueclam/iiim compactam, Bnj- 

 oxiphiiim norvcgiciim and Anthelia spp. The piants from these habitats 

 were quite sterile, and exactly alike in all respects. 



The fruit, which is common in the Alpine form, ripcns in August 

 (Akureyri: ripe Aug. 13th; near Isafjordur: green in the first half of July). 



204. Polytrichum piliferum Schreb. 

 Polijtrichiim pilosiim Neck. 



Iceland (Morch)!. E. Iceland: Vallanes (H. J.;!). N. Iceland: Rey- 

 kjahlid (Grl.;!). NW. Iceland; Bildudalur (C. Hansen;!); Gnupr near D\ra- 

 fjordur!; Armulil; Arngerdareyri!. W. Iceland: Stykkisholmur (H. J.;I); 

 Grund in Skorradalur!; common near Reykjavik! ; Videy!; Hafnarfjordur 

 (Wiinstedt)!. S. Iceland: Krisuvik iStp.;)!; Drangshlid!. 



Occurs here and there, and is rather rare in the majority of the 

 districts of Iceland. It grows on dry sandy ground, upon soil-covered 

 rocks and on dikes, often singly among other mosses. It is absent from 

 or rare in the most rain}' parts of the country, for instance at the East 

 coast and in South Iceland and is most frequent in those districts where 

 the rainfall is least. Thus it occurs abundantly near Mwatn, where it 

 is common in the lava-field. It is also rather widely distributed in 

 NW. Iceland, here it is often found in abundance, for instance on sandy 

 fieids near Armuli and on rocks near Arngerdarejri. Fruit is common 

 and ripens in the latter half of June. 



205. Polytrichum juniperinum Willd. 



Conimonly distributed. 



It grows on more or less dry ground, for instance on knolis in 

 bogs, in the Rhacomitrium-canescens heath, on slopes among Hylocomium 

 and Rhacomitriiim elc. , usually scattered among other mosses, more 

 rarely in cohering tufts, and almost always sets fruit which ripens at 

 the end of June and in the beginning of July (Seydisfjordur, July 6th; 

 Isafjordur, June 24th). 



It is most widely distributed in the lowlands and does not appear 

 to ascend much higher than about 400 metres above sea-level. 



